Firebase: Setting User Property to Null or blank value not deleting the userproperty

I am trying to delete or set the user properties when I logout from the app but after setting the user properties to null or blank user properties still persist in Firebase console.

This is code snippet I am trying.

    mFirebaseAnalytics.setUserId(null)
    mFirebaseAnalytics.setUserProperty("user_age", null)
    mFirebaseAnalytics.setUserProperty("user_gender", null)
    mFirebaseAnalytics.logEvent(FirebaseConstants.Events.LOGOUT, bundle)