Any tips on removing alternator and belt E46

hi guys

i am trying to replace the oil filter housing gasket but in order to do that need to remove my belt and alternator...

any clue as to how to get belt off (from what it looks like there is a super long bolt holding the belt and goes into the alternator.....i dont have a tool to remove the fan so space wise its a bit tricky...

any tips for removal please...