If you want to delete your Gmail account, follow these steps to do:

– Go to Google Account Settings

– Open the Products page

– Click Edit under Your products

– Click Remove Gmail permanently under Delete a Product

– You can also choose Close account and delete all services and info associated with it to remove your entire Google account (ex: Google Docs, iGoogle page, AdWords and AdSense as well as other Google services)

– Check at: Yes, I want to permanently delete …..@gmail.com and remove it from my Google account

– Enter an email address different from the address associated with the account you are closing under New primary email address.

– Gmail may already have entered the secondary address you used when creating the Gmail account

– The alternative email address becomes your new Google account user name

– Make sure you enter an email address to which you have access. You need that access to complete deleting your Gmail account

– Enter your Gmail password under Current password

– Click REMOVE GMAIL

– Open the “Gmail Removal Confirmation” email from “accounts-noreply@google.com” at the email address you specified as your new.
– Follow the deletion link in it.

– Type your Gmail password under Password
Click Verify: Keep in mind that you cannot undo this step

Note: Now any people who mail your old Gmail address will get back a delivery failure message.

>> Read How to back up, then delete your Google account

Via: About.com