You can add and remove your Google accounts in the same way as you add/remove your store accounts but by using the “Google Accounts” tab instead. Here you will find an identical layout, the only difference is when you click “Add Account” you’ll see a Google sign-in window, inside this window you’ll need to log into your Google account and then input a name and email address in the fields below the window itself. Once done click “Save” and your account will be stored.
Once you’ve added an account you’ll see the following icons beside it in the column, clicking the "Google" icon will launch your account inside a pop-up so you can ensure it's logged in correctly, the "Edit" icon allows you to edit the assigned proxy or even relogin into the account (Useful after a password change for example). Lastly, you can remove the account by clicking the "garbage" icon.