Apple Launches Tool to Remove Phone Number from iMessage
If you have switched from the iPhone to another device or just got rid of an iPhone and that phone number, you may notice that that phone number still shows up as an option within the iMessage settings. Also, others who have switched from an iPhone to to another phone may have noticed that they can't get SMS messages from iPhone users because it's trying to send it via iMessage.
Now, Apple has launched a new web tool that allows you to deregister your phone number from iMessage. To use this tool all you need to do is go to this page and enter you phone number. Then they send you a free text message that contains a code to enter into the site and remove that number from your iCloud account.