How do I delete a backer?
Deleting a backer is generally frowned upon, it is typically a better idea to mark them as canceled. This clears information and prevents them from getting a survey/emails, but keeps a reference to their original pledge in case you need to track things for any reason. You can mark them as canceled on their backer profile.
If for some reason you do need to delete someone (for merging several IndieGoGo pledges into one or removing a duplicate preorder) you can do that under the actions drop down. (Canceling pledges noting this marks all pledges with that email, so if they have two/three IndieGoGo pledges it cancel all of them.)
If you are unsure as to which option to use, default to refunding or email email@example.com for advice.