You can delete Gmail from your Google Account at any time. If you’re sure you won’t use Gmail in the future, please follow these steps to delete it:
- Sign in to your Gmail account.
- Click on your name or email address at the top of the page, then select Account settings from the drop-down menu.
- In the “My products” section, click the Edit.
- Click Delete Gmail Service and fill in the required fields. [source]