How can I reverse my brake handles?

For the 10+ years I've owned this 87 Centurion, my rear brake has been on my left, and my front brake on my right. I just brought it to the mechanic to get the brake cables replaced (pretty disappointed they didn't ask if I wanted to stick with white like I had originally) and the mechanic reversed the handles to the correct way, so now my left controls my front brake and my right controls the rear.

I'm way to used to riding the way I have, so is it easily possible for me to just slide the brake handle off and switch them? Or do I need to bring it back to the mechanic?

Thanks

My brakes look like this. I'm not seeing anywhere I can unscrew something to get them to move. All I really have for tools are screwdrivers and a wrench.