Cut it off....and then don't worry about it.
That's mostly a joke. I have a lot of guns out on racks. I use trigger locks, not to protect the gun or stop thieves, but to protect grandkids and other people who's education and conduct I am not fully in control of.
I have several "safes" that are really just gun cabinets, and guns without a trigger lock or a cable go in them.
It's just me and the wife at home now, so I DO have a few guns that are not "secured". They are hidden, or out of reach, and some get moved when the little ones come home.
I would bet money that if you went to a dealer and asked, they'd give you a new lock for free.
In my AO, many of us walk out the door with the required lock they must include with a newly purchased gun, new or used, then turn around and walk back in to give "this lock I just found out on your entrance" back to the counter guys.