Hacked usage of recovery mail

As of recent i received some mails regarding some of my accounts which most have been fixed. Main problem now is that my gmail account (******@gmail.com) is being used as a recovery mail for an old account of mine which i want to delete but don't have access to, and 2 other accounts which aren't mine, causing suspicion on my end. I only want to be able to remove that connection between my gmail account and those 3 outlook accounts.