How to remove toolchains from Android NDK?

I've lots of Android NDK revisions, starting 6 up to latest 14 (to test building of native code). In order to save storage space i've deleted mips* toolchains from ./toolchains/ (from android ndk 10c to be more detailed) as i don't need them for sure.

Now while trying to build library code with Gradle i'm getting the following error:

No toolchains found in the NDK toolchains folder for ABI with prefix: mipsel-linux-android

though in Application.mk i have only armeabi-v7 and x86:

APP_ABI := armeabi-v7a x86

In build.gradle i have :

android {
  compileSdkVersion 16
  buildToolsVersion "25.0.0"

  defaultConfig {
    ...

    ndk {
      abiFilters 'armeabi-v7a', 'x86'
    }
  }

  externalNativeBuild {
    ndkBuild {
      path 'jni/Android.mk'
    }
  }

  ...
}

How can i delete unnecessary toolchains properly?