I am fairly certain that it is illegal not to allow disabling of overdraft protection. When I went to my old bank's branch, I asked for it to be turned off, and they said "We need a letter written to this effect."

I asked for a piece of paper, addressed the branch manager, and asked in a sentence to disable it for my account. They seemed perturbed that I would do this while the line was waiting behind me, but frankly, it's their policy.

I had it turned off immediately.