Compromised apple id

Hi, my husband is getting emails from an Apple ID he no longer uses. It’s clearly compromised and has now been used to log into his iPhone. The recovery email mentioned in the email he received is clearly not his and we think the password has been changed. He no longer uses this Apple ID and doesn’t think any valid credit cards would be attached, so the easiest thing to do is delete the account but as he cannot log in this is proving difficult.

Can you help?

thanks!