1. Click on the settings.
2. Click on accounts.
3. Click Google.
4. Click on the email address that you want to remove.
5. Click on the three dots at top right hand corner.
6. Finally click on the remove account.
That's it! That's how you remove an account from an andriond tablet. I did this on my Nexus 7.
If you are thinking about how to add an accout, then that's simple too. Just click on Settings >> Accounts >> Add account and simply follow the instructions.