Go back to it in Settings and untick the box.
Where this is varies. For a long time it was a global setting in a place like the Security settings. In the latest Android it's in Settings > Apps > Advanced > Special App Access, and there you remove the permission from all apps you have granted it to (because the way it's managed changed, so you now explicitly authorise particular apps rather than authorising all apps that have the capability). I don't have this phone so don't know which method it uses.