The method will take care of the actual deletion process in the avatar manager.
Additionally, we'll be using a confirm box while deleting the avatar to prevent
users from accidentally deleting their avatars.
PHPBB3-12822
The tests were reduced to only test one case that should be correct and one
that should fail. Different test cases have been split up over the specific
test files for the acp groups, acp users, ucp groups, and ucp users page.
PHPBB3-11531
