I removed some of the black metallic covering of my pan, is it still safe to use?
Looking at the close-up, I'd say that the 'black stain' is where the actual non-stick Teflon coating has already been scratched off.
The bare metal is where you finished the job &amp; also removed the substrate, which was probably used to get the Teflon to stick to the aluminium.

I think you've reached the point where it's simpler to just throw it in the recycle &amp; buy a new one.
Treat it more gently next time - never use metal utensils or scourers on Teflon. Non-Stick tends to only be good for a couple of years at best, so you need to weigh up how much you're willing to spend on one… every couple of years.