Both actions are in My account, tab Data (open it).
Export your data
Click Export to receive a copy of your account information and your processing history.
Delete your account
Click Delete my account, then confirm. This cannot be undone: your account, videos and settings are erased for good.
If you have a subscription: A subscription paid on the website is stopped immediately, with no refund for the current period. To use it until it ends, cancel it in the Subscription tab instead. To keep your access until the end of the period you paid for, cancel your subscription first instead. A subscription taken on the App Store or Google Play is managed in that store.