Fenders come off really easily. There are like 8 bolts (maybe more maybe less) that need to come out, three of them are a little trickier than than the others since the door is kind of in the way, and then you just pull it off being careful not to scratch the door.
Once you have it off you'll see that it's easier to straighten out. Honestly though if the fender is too bent it'll never be the same. I think I would look for a used one to primer and paint if it were me.