How to logout from Gmail remotely?

If you are using Gmail from more than one location and need to sign out gmail remotely, here is the trick. Clicking the Details link next to the Last account activity line at the bottom of any Gmail page shows information about recent activity in your mail.

Recent activity includes any times that your mail was accessed, using a regular web browser, through a POP client, from a mobile device, etc.

If your mail is currently being accessed from another location, you can see the list of other session(s) in the Concurrent session information table. This could mean that you simply have another browser window open with Gmail loaded, or that your home computer is logged in to Gmail while you're accessing your mail from work. If you're concerned about any concurrent access, you can sign out all sessions other than your current session by clicking Sign out all other sessions.

Securing your Gmail:

Also If you're concerned about unauthorized access to your mail, you'll be able to use this data to find out if and when someone gained access. The IP address column is useful to check the unautorised access. If you always or most often sign in to Gmail using a single computer, your IP address should be the same. If you're seeing an IP address that differs greatly from your usual IP address, it could either mean that you've recently accessed your mail from a different location, or that someone has accessed your mail. Your current IP address is displayed below the Recent activity table.

If you get any doubts that your mail is accessed by other people, immediately change the password and security question.