diff --git a/README.md b/README.md
index 3aabae2..3b91ac8 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ Plugin for downloading and uploading translations from <a href="https://www.ones
 </p>
 
 <p align="center">
-    <img src="https://img.shields.io/badge/version-1.1.0-blue.svg">
+    <img src="https://img.shields.io/badge/version-1.2.0-blue.svg">
 </p>
 
 ## Installation
@@ -12,7 +12,7 @@ Plugin for downloading and uploading translations from <a href="https://www.ones
 **app/build.gradle.kts**
 ```kotlin
 plugins {
-    id("co.brainly.onesky") version "1.1.0"
+    id("co.brainly.onesky") version "1.2.0"
 }
 
 // ...
@@ -35,6 +35,12 @@ configure<OneSkyPluginExtension> {
 | **downloadTranslations** | Downloads all of available translations (including not finished ones) |
 | **uploadTranslations**  | Uploads base translation files |
 
+Add `-Pdeprecate-strings` if you would like to deprecate strings on OneSky which are not present in `sourceStringFiles`.
+
+```bash
+# deprecates removed strings on OneSky
+./gradlew sample:uploadTranslations -Pdeprecate-strings
+```
 ## Releasing
 
 See the release instructions [here](HOW_TO_RELEASE.md).
@@ -46,7 +52,7 @@ See the release instructions [here](HOW_TO_RELEASE.md).
 ./gradlew clean plugin:build plugin:publishToMavenLocal
 
 # run a sample
-./gradlew sample:translationsProgress --refresh-dependencies
+./gradlew sample:translationsProgress
 ```
 
 ## License
diff --git a/plugin/build.gradle.kts b/plugin/build.gradle.kts
index de4fa29..18032d5 100644
--- a/plugin/build.gradle.kts
+++ b/plugin/build.gradle.kts
@@ -10,7 +10,7 @@ plugins {
 apply(plugin = "org.jlleitschuh.gradle.ktlint")
 
 group = "co.brainly"
-version = "1.1.0"
+version = "1.2.0"
 
 gradlePlugin {
     plugins {
diff --git a/plugin/src/main/java/co/brainly/onesky/OneSkyPlugin.kt b/plugin/src/main/java/co/brainly/onesky/OneSkyPlugin.kt
index e4c9d3d..126d865 100644
--- a/plugin/src/main/java/co/brainly/onesky/OneSkyPlugin.kt
+++ b/plugin/src/main/java/co/brainly/onesky/OneSkyPlugin.kt
@@ -1,6 +1,7 @@
 package co.brainly.onesky
 
 import co.brainly.onesky.client.ONESKY_API_URL
+import co.brainly.onesky.task.DEPRECATE_STRINGS_FLAG
 import co.brainly.onesky.task.DownloadTranslationsTask
 import co.brainly.onesky.task.TranslationsProgressTask
 import co.brainly.onesky.task.UploadTranslationTask
@@ -45,7 +46,8 @@ class OneSkyPlugin : Plugin<Project> {
                 description = "Displays current progress from OneSky, skips already finished translations"
             }
 
-        tasks.register("uploadTranslations", UploadTranslationTask::class.java, extension)
+        val deprecateStrings = project.hasProperty(DEPRECATE_STRINGS_FLAG)
+        tasks.register("uploadTranslations", UploadTranslationTask::class.java, extension, deprecateStrings)
             .configure {
                 group = Constants.TASK_GROUP
                 description = "Uploads base \"sourceStringFiles\" to OneSky"
diff --git a/plugin/src/main/java/co/brainly/onesky/client/OneSkyApiClient.kt b/plugin/src/main/java/co/brainly/onesky/client/OneSkyApiClient.kt
index b6f65ef..83dc860 100644
--- a/plugin/src/main/java/co/brainly/onesky/client/OneSkyApiClient.kt
+++ b/plugin/src/main/java/co/brainly/onesky/client/OneSkyApiClient.kt
@@ -68,14 +68,20 @@ class OneSkyApiClient(
         return fetch(request)
     }
 
-    fun uploadTranslation(projectId: Int, file: File): Result<String> {
+    fun uploadTranslation(projectId: Int, file: File, deprecateStrings: Boolean): Result<String> {
+        val isKeepingAllStrings = if (deprecateStrings) {
+            "false"
+        } else {
+            "true"
+        }
+
         val url = baseUrl.newBuilder()
             .addPathSegment("projects")
             .addPathSegment(projectId.toString())
             .addPathSegment("files")
             .addAuthParams(apiKey, apiSecret)
             .addQueryParameter("file_format", "ANDROID_XML")
-            .addQueryParameter("is_keeping_all_strings", "true")
+            .addQueryParameter("is_keeping_all_strings", isKeepingAllStrings)
             .build()
 
         val body = MultipartBody.Builder(boundary = "onesky-gradle-plugin-file")
diff --git a/plugin/src/main/java/co/brainly/onesky/task/UploadTranslationTask.kt b/plugin/src/main/java/co/brainly/onesky/task/UploadTranslationTask.kt
index 0b3a88c..1d04cdc 100644
--- a/plugin/src/main/java/co/brainly/onesky/task/UploadTranslationTask.kt
+++ b/plugin/src/main/java/co/brainly/onesky/task/UploadTranslationTask.kt
@@ -11,8 +11,11 @@ import org.slf4j.LoggerFactory
 import java.io.File
 import javax.inject.Inject
 
+const val DEPRECATE_STRINGS_FLAG = "deprecate-strings"
+
 open class UploadTranslationTask @Inject constructor(
-    extension: OneSkyPluginExtension
+    extension: OneSkyPluginExtension,
+    private val deprecateStrings: Boolean
 ) : DefaultTask() {
 
     private val projectId = extension.projectId
@@ -35,6 +38,10 @@ open class UploadTranslationTask @Inject constructor(
     fun run() {
         progressLogger.start("Uploading translations", "")
 
+        if (deprecateStrings) {
+            logger.warn("Deprecating strings on OneSky which are not found in base files.")
+        }
+
         files.forEachIndexed { index, filename ->
             progressLogger.progress(
                 "$filename (${index + 1}/${files.size})"
@@ -44,7 +51,11 @@ open class UploadTranslationTask @Inject constructor(
 
             logger.warn(baseTranslationFile.absolutePath)
 
-            val result = client.uploadTranslation(projectId, baseTranslationFile)
+            val result = client.uploadTranslation(
+                projectId,
+                baseTranslationFile,
+                deprecateStrings = deprecateStrings
+            )
             result.handle(
                 onSuccess = { /*do nothing*/ },
                 onFailure = { error -> onUploadFailure(filename, error) }
diff --git a/plugin/src/test/java/co/brainly/onesky/client/OneSkyApiClientTest.kt b/plugin/src/test/java/co/brainly/onesky/client/OneSkyApiClientTest.kt
index bb0c2f9..1167648 100644
--- a/plugin/src/test/java/co/brainly/onesky/client/OneSkyApiClientTest.kt
+++ b/plugin/src/test/java/co/brainly/onesky/client/OneSkyApiClientTest.kt
@@ -105,7 +105,7 @@ class OneSkyApiClientTest {
         val file = File.createTempFile("onesky", ".tmp")
         file.writeText("Hello OneSky Gradle Plugin")
 
-        client.uploadTranslation(projectId, file)
+        client.uploadTranslation(projectId, file, deprecateStrings = false)
 
         val request = server.takeRequest()
 
@@ -137,4 +137,42 @@ class OneSkyApiClientTest {
             request.body.readByteString().utf8()
         )
     }
+
+    @Test
+    fun `uploads a translation file and deprecate old strings`() {
+        val file = File.createTempFile("onesky", ".tmp")
+        file.writeText("Hello OneSky Gradle Plugin")
+
+        client.uploadTranslation(projectId, file, deprecateStrings = true)
+
+        val request = server.takeRequest()
+
+        assertEquals(
+            "/projects/41994/files?api_key=my-api-key&timestamp=12" +
+                "&dev_hash=28dac32cc9ee8ab264d35087653be23e&file_format=ANDROID_XML&is_keeping_all_strings=false",
+            request.path
+        )
+
+        assertEquals(
+            "POST",
+            request.method
+        )
+
+        assertEquals(
+            """
+            --onesky-gradle-plugin-file
+            Content-Disposition: form-data; name="file"; filename="${file.name}"
+            Content-Type: application/octet-stream
+            Content-Length: 26
+
+            Hello OneSky Gradle Plugin
+            --onesky-gradle-plugin-file--
+
+            """.trimIndent().replace(
+                "\n",
+                "\r\n"
+            ), // to avoid conflicts with OkHttp
+            request.body.readByteString().utf8()
+        )
+    }
 }
diff --git a/sample/build.gradle.kts b/sample/build.gradle.kts
index 9bd2691..3715083 100644
--- a/sample/build.gradle.kts
+++ b/sample/build.gradle.kts
@@ -11,7 +11,7 @@ buildscript {
 plugins {
     id("com.android.application")
     kotlin("android")
-    id("co.brainly.onesky") version "1.1.0"
+    id("co.brainly.onesky") version "1.2.0"
 }
 
 android {