removing wall-mounted corner shelf?

The former owners of my house put a small triangular shelf into a corner space in the kitchen. Great idea, but I would like to have it about two inches higher to maximize usable counter space, and it is not level so anything I put on it is in danger of sliding off. Because it is not level, I assume it was not part of the original construction, but a "handyman" project.

I want to remove/reposition it. Problem is, I can't figure out how it's mounted. I see no supports under the shelf, and can't find evidence of any screws going through the shelf itself into the wall. I thought it might be simply glued on, but if it is that's some super-strong glue, because I can't get the shelf to even wiggle.

How might this be mounted/affixed, and what is the removal technique most likely to result in the shelf being removed without the wall being destroyed? I know I'll have to patch and paint, but I'm hoping to accomplish this without any knocking gaping holes in the drywall.

Thanks!