I’m wondering how one would remove or Banish the entity Beleth after it has been in ones life for a few years without any known agreed upon spirit contracts?
First you could start with an LBRP , then you’d want to work with a divine spirit for help , try picking one of The Seven Archangels . If you have some form of pact with that spirit , you’d want to make sure to meet it otherwise there could be dire consequences , sometimes you could simply take the route of asking the spirit why he is bothering you , if he takes the aggressive route however you must defend yourself .
The same way you’d remove a human relationship - you can ghost, or you can communicate that it’s over.
Getting into ritual to have the conversation about going your separate ways and why would, I think, be the decent thing to do for someone that’s been with you for years.
Banishing would be the equivalent of blocking them on social media. Only, because it’s a spirit they’ll probably know why.