You may want to delete your Gmail account for several reasons but whatever your reason may be, be sure to take necessary precautions because after you delete your account it could be irreversible. You might not be able to recover it ever again.
Also know that when you delete your Gmail account, all data, contents, services and every other thing you signed up with that account will be lost. So be careful and follow the guidelines when deleting your Gmail account.
If your account has been hacked and you wish to delete it, consider using Security Checkup to learn more about what parts of your account were accessed without your permission. That way, you can take steps to reduce further harm caused by the hacker.
Also, you may want to Review & download your info before you delete your account. Download data that you want to keep. If you use your Gmail address for online banking, social media, or apps, add a new email address for these services. Update your account recovery info in case you try to recover your account later.
After these, you can now move to delete your account with these steps:
Go to myaccount.google.com.
At the left, click Data and personalization.
Scroll to “Download, delete, or make a plan for your data.”