This drove me insane yesterday!!! Simple task of dropping logins from one domain after adding accounts from another domain became a chore when 2 accounts failed to dropped because:
Login 'XXXX\XXXXXXX.xxxxxxx' has granted one or more
permission(s). Revoke the permission(s) before dropping the login.
I tried so many things like revoking granting ability from the acccount after searching who the accounts granted rights to (me!?!) Revokes rights from my account and on and on with no luck. I got frustrated and went home in disgust!!! SO I read that if all fails, drop the account (MINE!!!) that perms were granted to and voila the accounts dropped!!! Buzha!!!