If it can be done, it can be undone.
My go-to method uses sympathetic magcik to represent the connection or in this case what looks like a binding and destroy the poppet. That’s here: Mulberry's "destroy an unwanted connection / relationship using a poppet" tutorial
But if this is a binding, then Mehmi’on (from the Book of Azazel) is been successful for me to remove bindings placed on me by a witch. Mehmi'on - regarding bindings on the practioner
Death curse. Now these usually take ages and often fail from lack of will to actually kill, but in this case that can be an advantage - you can deliberately modify the intention to curse the target to make it as if the target were dead as far as you’re concerned. They don’t have to actually die if vengeance isn’t a factor. This means you don’t have to get drastic, and the working is more achievable, as it opens up more paths to manifestation for faster results.