Removing Google account from TikTok

Trying to disconnect my Google account from TikTok. There doesn't seem to be a clear way of doing this, it seems you're supposed to do it by getting rid of the email you can see in account information, but this happens to be my other non-Google email address which I intend to keep on the account after removing the Google account. I know the Google account is still connected though, because I can use Google to log into the account as well as the alternative email address; yet there's no clear way of removing the Google account, because it looks like it's been overwritten by the other email, but they're definitely both connected.