Two of three stalks on my plumeria shriveled up over winter. Look unlikely to revive. Safe to cut them off? The stalk on right seems fine.

Still looks okay, as long as no mushy part anywhere. But if those tips are oozing black stuff, I would cut to healthy part and allow to dry.

I agree! Those tips all look dark, but that may just be the lighting. In either case, only cut back to healthy growth and you may get more branching at the point of the cut. Do give it some time though. Winter is tough on tropical, but they often recover once the temps go up and the sun comes out.