hide my email

I have 2 Gmail accounts they both have access to my Contacts in my Mail . also I have the Gmail app. However I never knew about hide my email private email address with iCloud so when I try to add one of my Gmail’s to my iCloud account it says it’s already in use. If I turn off Contacts get rid of my Gmail app don’t sign into Google or anything you know just quit using one of those emails can I then use one of those emails as my email domain? When I put it in now says it’s already in use which it obviously is because it is an active email for me. I drealize I do not need to Gmail’s and I really don’t need to email if I’m using the Mail Mail app.

For your help, I noticed after looking into it further the hide my mail is actually came with iCloud+ so I accidentally upgraded my iCloud and I guess that’s why I’m saying that now I’ve never seen it before. I thought maybe it was always there and I didn’t notice it or it came with the iOS update however, after further reading it comes with iCloud+, so I just wanted to let you know, and thank you again for your help that your information helped me a lot actually.