If you no longer wish to use your you tube account and you want to delete it, then below are the instructions.
Instructions to delete youtube account
Step 1: Sign-in to your Youtube account.
Step 3: Click the “Manage Account” link on the Account settings page. (Located at the left side of the page)
Step 4: Click “Close account” as show in the below picture.
Step 5: Provide the reason for closing your youtube account. Note: Closing the youtube account will delete all the videos, comments and subscription made. But your google account will not be deleted.
Closing your youtube account will permanently remove your videos, comments and profile information from YouTube. You will not be able to create the Youtube account with the same username.