Hi CyndiLou, Sorry to hear about your company closing. Please contact Stamps.com Customer Support to close your account. You can reach them by calling toll free at 1-888-434-0055 (open Mon-Fri, 6am to 6pm PT) or by emailing social(at)stamps.com.
Our Customer Support agents can get your account closed so you are no longer billed.
Thanks!
Eric
Stamps.com