WinSMS.mobi
Open your browser and go to
www.winsms.mobi and log in with your WinSMS and username.
Click on the menu button in the top left-hand corner.
Click on Inbox.
Click on the opt-out message, then click on "Delete Contact"
Click on "OK" on the confirmation screen.
Congratulations, you have just removed an opted-out number from WinSMS.mobi
Don't have a WinSMS account yet? Register your free trial
account here.