Well, I’m not an expert on banishing spirits, because I never had a need for banishing. I still suggest doing a Lesser Baninshing Ritual Of The Pentagram.
…but, there’s really nothing that indicates this particular spirit to be a succubus/incubus. It seems to be a parasite with succubus-like tendencies. Don’t get me wrong. A succubus/incubus on the “wrong” side of the fence, can wreck havoc and do serious damage and they’re almost impossible to banish if they are deeply connected to their target. But this particular spirit/parasite isn’t one of them, at least as it’s described.
Of course you can try the “Letter Method”-ritual in reverse, empowering it with all four Queens, including Samael. You just have to figure out how to write that letter.