If you delete your Google Account, you'll no longer have access to Google Docs. You'll also lose any preferences associated with your Google Account for other services, such as Google Groups or Google Alerts. If the account is associated with a Gmail address, you'll also no longer be able to access that email account.
Additionally, after you delete your account, it's possible that residual copies of your files could take up to 30 days to be deleted from Google's active servers and may remain in Google's backup systems for up to an additional 60 days.
Instructions for deleting a Google Account are posted in the Google Accounts help center.