Go to your Google Account page
Sign in if prompted
Open the Security section
Under Your devices, select Manage all devices
Review the list of devices
Select the device you want to sign out from
Click Sign out
Repeat for each device you want to remove
Change your Google Account password to sign out most devices automatically
Turn on 2-Step Verification for added security
Check for any unfamiliar devices or activity
Remove any recovery methods you no longer use