Email addresses used with Apple IDs have a waiting period before they can be used again with another Apple ID.
Apple does not provide any specific time frame,s but people have found having to wait between 30 days and up to a year before the email address is released from the system and can be used with another Apple ID.
Beyond waiting and seeing if it becomes available at some point, your only other option is to get a new email address that has never been used with an Apple ID before. There are several free providers including Yahoo, Outlook, and others.