Your new Apple ID cannot be the same as your notification email address

Apple hasn’t published any guidance for using an address again. Normally, if your e-mail address was associated with an ID in any way, for example as a Notification email address or a Rescue e-mail address, then it can't be reused with another Apple ID for approximately one year. I have also seen posts that stated Apple told them there was a 30 day waiting period before the address could be used again.  You will need to get another e-mail address to use as your Apple ID or you can try waiting 30 days to see if that works.

You will have to remove this from your Apple ID account page first.

To do this here is how:

About your Apple ID email addresses

Delete a rescue email address

1. Sign in to your Apple ID account page.
2. Click Edit in the Security section. You might be asked to answer one or more security questions before you continue.
3. To delete a rescue email address, click  next to the address.

Good luck!