do this trick

whenever guide appear, build a room specifically where he canot escape from (as in go up or down)

then let him die by zombies, lava whatnot.. hell automatically respawn there then you can leave your main door closed forever

normally to confine him to the room is by putting a block of dirt/wood/etc so he cant open door

another way is to place him in a room which is 1 floor above or several floors above. put wood platforms to prevent him from going down (i rarely see NPC jump unless got high obstacle like mountains)

both methods work well