My 9.3x62 have a small pitmark in its chamber, it it dangerous and can it be removed

No, not dangerous and it depends on how deep it is but it may be possible to polish it out. Maybe not. I'd just clean it up and shoot it. In the chamber it shouldn't affect anything.

Very light pitting in the chamber may be ok. Deep pits and rough chambers have the potential to cause some real problems. When a round is fired in such a chamber, the brass can expand and stick to the rough surface and make extraction really difficult.