After obtaining quotes for the work done in my home (plumbing, roofing, etc.), I never know how to tell the contractors will not use-thanks, but go with someone else. I do not want to leave them hanging, but I also do not want to seem like I'm playing the contractors against each other. Essentially – No need for a "thanks, but no thanks" to offers that have been rejected. If you call, let them know you accepted another offer. But the need to reach them, no. It's just part of doing business and not owe anyone an explanation. Nor are they expecting one. Good luck on your project. Hope this helps.