What alternatives are there for relinquish or abdicate in a business setting?
Business X is willing to [relinquish] their preexisting partnership for this opportunity.
How about "cede"?
Or keep it simple: "end"
I'm guessing that if you want words that are less extreme than "relinquish", words like "terminate" and "abort" are probably not good choices.
You could also go with word like "nullify" or "cancel". I'm not sure they carry the meaning you want in this context, but they might work.