Second email in Apple ID
I have a second email in 'Reachable at' which is an xxx@icould.com email, that is different from my actual email. I must have accidentally done something at one time to set this up, but mail is being sent from that wrong email instead of the one I want it to come from. I've gone into appleid.apple.com to try and manage under the appleid@apple.com but the one I want to get rid of is greyed out and says 'This is an alias of your Apple ID email address'. If I go into icloud.com and click on Mail and try to Edit the Account to change the password then it doesn't give me an edit option, just the option to create an alias with @icloud.com as the ending of the email address. I can log into Appleid and iCloud.com using both email addresses though? It gives the same info for each when I do, as though they were the one and the same email. I want to get rid of the extra one linked under my Apple ID but can't edit it anywhere as it won't allow me. Help please!!
iPad Air, 12