Visit http://myaccount.google.com and sign in. On the right side is a link to click to delete your account and all the data associated with it from Google's servers.
If you are asking how to remove an account from a phone (while keeping your account with Google active), go into settings, choose accounts, select Google and you should see it there to remove it from the phone. To do that, tap the account to open the sync settings for the account, tap the overflow menu (3 dots, top left corner) and select to remove the account.