You must first get into your account to be able to delete your channel, because if you can't get into your account then you might not get to the delete tab.you can start with inputting an email you can remember and clicking on the forgot password to see if you can have access to the channel.Then you can follow these steps. Get into the YouTube account and get to your account tab setting look for delete this account at the bottom of the page and click on it and the delete account page will open and you will be prompted to write why you need to delete your channel, I think the YouTube team just want to know why you no longer what to use their product and maybe makes amends if need be. You will be asked to enter your password and you can finally click on delete channel and your request will be granted.