If you cut of circulation in your leg, could that lead to needing your leg cut off?

Possibly. If circulation is entirely cut off, it needs to be repaired immediately. Otherwise, the tissue further away from the blockage will be starved of oxygen and nutrients leading to gangrene (death). This can threaten your life and at that point, amputation will be necessary.
Yes but y would u do. Yes it would lead to tissue necrosis (death and gangrene) but why would you do that?