The shelves themselves are probably just sitting on the brackets. Just lift them off. They may be stuck by multiple layers of paints. Use a hammer and hit upwards from underneath the shelf to loosen it up.

Then the brackets are nailed into the wall. It looks like you can see some nails a couple of inches back from the front of the shelf. But again, multiple layers of paint are probably 'gluing' the bracket to the wall. You aren't going to remove it without some damage to the wall. Use a prybar and a big flat wood board to pry against (so that the pry bar isn't pushing directly against the drywall) and a little elbow grease.

Use a magnet and you will find all the nails.

Thanks for your replies. I will give the your removal tips a whirl this weekend! Appreciate your advice.

Use a thin sharp knife to cut paint along edges of the shelf support board before removing. Will help prevent damage to drywall.

I’m about to do this exact thing. What tools did you use? I’m trying to prevent wal damage too. They’ve likely been on there since early 90s. 😞

Meghan this is the best trim or shelving support removal tool on the market today used by most professionals and it will not cause any damage to the wall, just use @ stud locations and if nails been painted over and nail holes are not visible, like I said before in the previous post use a magnet.Here is the link, you can find this tool on Amazon for $23.

Good luck