If you really want to delete your account, you can do so on your Airtable account page. To get to your account page, click the circular face icon in the top right of the home screen. This will bring up a dropdown menu with several options; select the Account option (which has a little silhouette of a head next to it).
This will bring you to the overview section of your account page. You can also go directly to https://airtable.com/account.
At the bottom of the overview section of your account page, there is an option you can click that says "Delete your Airtable user account."
For security reasons, you will then be required to sign in with your email and password again.
After successfully signing in again, you'll be brought to a final screen—click the red button that says "Yes, confirm deletion of my account."
Please note that if any of your teams or databases are shared with other people, deleting your account will not delete those teams and databases. In order to delete those teams/databases, you must first remove all shared users from each of those teams/databases, and then delete your account.
Also note that if you are the sole owner of a team with multiple members, you will need to transfer ownership of that team to another member before deleting your account.