There is no immediate right or wrong to this but methinks you may be asking the wrong question. I would rather hear “Do I expect to ever work again?”
You don’t mention your age, but if you would like to earn a professional income again, and to aim towards enjoying work again, and can imagine at some point feeling well enough to do this, then what is needed now is some career guidance before any decision is made regarding the GMC.
If the answer is no to the question – and you are aged 63 and content not to work at all from now on, then it would probably make sense to de-register.