One my recent bank statements mentioned a phone number to call for removal from pre-approved credit solicitations. Since this came from a well known bank in a paper statement, I'm inclined to trust that it's not a scam.

Call the Prescreening Opt-Out Number
(888) 5OPTOUT = (888) 567-8688

One more steps to liberate our mailboxes, save waste paper, and save our time shredding/tearingup these unwelcome mailings.