1. Open any Web Browser and open www.google.com.
2. Click on Sign in at the top right corner of Google screen.
3. Enter your User Name and Password and then click on Sign in.
4. After signing in click on your account icon that appear at the top right side of Google screen.
5. Click on My Account.
6. Under the Account Preferences click on Delete your account or services.
7. Click on Delete Google Account and data.
8. Check both two checkboxes and then click on Delete Account.
9. Now your Google account and all its data deleted successfully.