Please read the corresponding article if you need to find out which email you are currently using.
If that is not the email you want to use, go to https://app.tactiq.io/ if you are not there yet. Then click on your name/avatar in the bottom left corner of the page and choose "Sign Out".
After this, you will be redirected to the login page, where you can sign in again with an account of your choosing.
Signing into the extension
Once you sign in, the extension will be signed in automatically. The same applies to signing out.