How to find all accounts linked to my email address
To find all accounts linked to your email address, log into https://myaccount.google.com/ and then select 'Security' on the left hand side menu. Then scroll down to "3rd party Apps with Account Access" and click on the "Manage third party access" link.
You can then remove apps which have access to your email account and you can remove websites which use your google credentials to sign in.
