Select the device, choose "More Options" and then "Customize the Device mode for this .

You'll see the device with the "Button" and "Custom Button Label" and their controls. In the device control column, simply select what you don't want thru the drop-down and remove it (scroll to the top and you'll see a blank selection) by selecting the blank. Once you click "Done" it will update. You'll then need to update the remote and extender.

You can also rearrange how they display on the remote here.