Delete you from all of your WhatsApp groups.
However, to register this phone number on WhatsApp Business API, you will need to follow the steps below to delete the WhatsApp account associated with that phone number. You can use a phone number that is already registered in the Android, iPhone, or Business application versions of WhatsApp. To apply for WhatsApp API Verification, you must use a number that does not have an account on any WhatsApp apps.