How to access system permissions REMOVE_TASKS?

Question

I'm designing an application for removing recents tasks. Because of the need to access system permissions like REMOVE_TASKS

and i got this in my log

Caused by: java.lang.SecurityException: Permission Denial: removeTask() from pid=12579, uid=10066 requires android.permission.REMOVE_TASKS

I am using this code:

public boolean removeTask(int taskId, int flags) {
    try {
        return (Boolean) mRemoveTask.invoke(mActivityManager, Integer.valueOf(taskId), Integer.valueOf(flags) );
    } catch (Exception ex) {
        Log.i("MyActivityManager", "Task removal failed", ex);
    }
    return false;
}

public void clearRecentTasks() {
    List<ActivityManager.RecentTaskInfo> recents = mActivityManager.getRecentTasks(1000, ActivityManager.RECENT_IGNORE_UNAVAILABLE);
    // Start from 1, since we don't want to kill ourselves!
    for( int i=1; i < recents.size(); i++ ) {
        removeTask( recents.get(i).persistentId, 0);
    }
}