If necessary, you can sign out of your Google account on all devices indirectly (or remotely). This process helps secure your account from others if you think someone has successfully accessed your account information.
Step 1. Visit Gmail
Go to https://mail.google.com in a browser and sign in to your account.
Step 2. Swipe down the screen
Click the link Details at the bottom of the screen.
Step 3. Click Sign out of all other web sessions
Step 4. Done
Keep in mind that the user you suspect can re-login to the account if he knows the account password or saves the password on another computer. If you're concerned that someone is using your account without your permission, it's a good idea to change your account password and not store the password information on your computer.