How to deregister from iMessage
After using Samsung Smart Switch to transfer data from an Apple™ device to a Samsung device, previous conversations that took place over iMessage™ can no longer be replied to and new iMessages from contacts will not br received by the Samsung device. You might not be able to receive text or MMS messages that someone sends you from an Apple device because they're still being sent as iMessage.
If you don't have your Apple™ Device or can't turn off iMessage™
After you deregister, your service number is removed from iMessage services. Text messaging should function as expected instantly, however in some cases this may take up to a few hours.
If you have other Apple devices, iMessages to your Apple ID will still be received by devices that have iMessage enabled.