Disable firebase crashlytics for Android

Disable Crashlytics at runtime

// Set up Crashlytics, disabled for debug builds
    Crashlytics crashlyticsKit = new Crashlytics.Builder()
    .core(new CrashlyticsCore.Builder().disabled(BuildConfig.DEBUG).build())
    .build();

    Fabric.with(this, crashlyticsKit);       

Ex

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Set up Crashlytics, disabled for debug builds
    Crashlytics crashlyticsKit = new Crashlytics.Builder()
    .core(new CrashlyticsCore.Builder().disabled(BuildConfig.DEBUG).build())
    .build();

    Fabric.with(this, crashlyticsKit);
    setContentView(R.layout.activity_main);

}

More

boolean Agrees = value;
if(Agrees)
{
    Fabric.with(this,new Crashlytics());
}
else
 {
   CrashlyticsCore core = new CrashlyticsCore.Builder().disabled(true).build();
   Fabric.with(this,  new Crashlytics.Builder().core(core).build());

throw new RuntimeException("why doesn't this show up in Firebase Crashlytics?");
 }

Edit 2

Ref : Fabric's Crashlytics with Firebase can't be disabled for DEBUG builds

The Firebase Crashlytics documentation explains that once reporting is enabled in an app session, it cannot be disabled.

By default, Crashlytics reporting is enabled in a ContentProvider named CrashlyticsInitProvider that executes before your Application instance is created. CrashlyticsInitProvider enables or disables reporting based on the meta-data value firebase_crashlytics_collection_enabled, which by default is true.

If you want reporting disabled, it's critical that the manifest meta-data be present and set to false:

<meta-data
    android:name="firebase_crashlytics_collection_enabled"
    android:value="false" />

Look in the logcat during app initialization for the message:

CrashlyticsInitProvider: CrashlyticsInitProvider initialization successful

If the message is present, firebase_crashlytics_collection_enabled is true. If the message is not present, you have successfully set the meta-data to disable crash reporting.

If the meta-data is missing or set to true, you cannot disable reporting in your code using a call to Fabric.with(...).

In a comment to another answer, you indicate that you tried disabling reporting using the meta-data and were not successful. Check for a typo and ensure the declaration is correctly placed in the <application> element. In my tests, I am able to disabling reporting using the meta-data and then enable at run time.

In your module build gradle...

    release {
        //true value to send the crashlytics to the firebase
        manifestPlaceholders = [crashlyticsCollectionEnabled: "true"]
    }

    debug {
        //false value to stop sending the crashlytics to the firebase
        manifestPlaceholders = [crashlyticsCollectionEnabled: "false"]
    }

In the manifest

 <meta-data
       android:name="firebase_crashlytics_collection_enabled"
       android:value="${crashlyticsCollectionEnabled}" />