How do you remove the battery from a 2000 Harley sportster?

Remove the seat.

There is a strap that goes across the top of the battery cover. Loosen this strap by removing the bolt and washer on the right side. Now you should be able to 'jiggle' the cover loose and remove it as well. It has 3 sides and should come off with a little work.

Pull battery out towards you at the top and you should see where terminals - etc - connect.