Disabling automatic sign-in
Stop sign-ins on Google accounts
Any time you sign in to your Google Account, you'll stay signed in unless you specifically sign out.
If you sign in on a device that's not yours, learn how to browse in private to help protect your account.
Stop sign-ins on non-Google accounts
You can also try to clear your browser's cache and cookies. Please note that while deleting your cookies may resolve the problem, it will also remove your saved settings for sites you've previously visited.