[Hocrest]

If the belt is still inplace, I have "tensioned" the tensioner before removal. Use a small pry bar to put pressure on the tensioner while someone loosens the two bolts holding the tensioner in place. Then slowly and gently use the prybar to compress the tensioner and have someone stick a small allen wrench in the lock hole.

At that point, the tensioner can be removed and the belt can easily come off.

Or you can just undo the bottom pulley while it is tensioned and then use a vise to compress the tensioner.