Is there a reason

[SendohJin]

Why is someone sitting afk in your house a problem?
Is it not possible to lock the house? (I do not own a house, so no idea).

You can close your house to everyone but yourself but you can't lock out just 1 person.

Is switching servers not feastable? Or starting on a new account?

that's crazy that anyone has to do this to avoid another character.