Well this is a general guide to migrate your WhatsApp old account to a new number. Performing the action will will migrate your account info, groups and setting.
As recommeded by Whatsapp you will need to confirm that you are able to recieve SMS or call at your new number. And if you have both new new phone and a new number then it is recommended that you first change your number on your old phone.
Tap on Menu > Settings > Account > Change Number and enter the old phone number in the first box, followed by the new number in the second one.
Go to Settings > Account > Change Number, Enter your old phone number in the first box, and your new phone number in the second box.