Apple ID
I forgot the password to one of my other iCloud but I do the forgot password and then it ask for a phone number I no longer have so I’m unable to log in
iPhone 8 Plus
If the email option won't work, contact Apple ID Support.
Apple Support by e-mail or chat Work through the screens to get a chat option. You may need to pick a problem that is slightly different than yours to get a chat option.
Or fill out and submit this form. The form is for iTunes, but it will get passed to the ID Support section.