My Realm is being hacked

Hi, My minecraft realm is being hacked by an unknown user. His gamertag doesn't show up on the list of players that are currently members of my realm therefore I cannot block him from the realm. He has multiple accounts (FartyYarty42, Avidbbq, SlinkyTexas19702 and possibly more) and I suspect he is using backdoor to get into the realm. Is it possible to move my realm to another server or delete his accounts. He is still continually disrupting my realm.