If you want to delete/remove Booking.com Account completely, than simply follow the given below steps:
1. Login to your Booking.com account
2. Now go the Booking.com Delete account page and than click on “Yes, remove my account” button
3. Now “Account marked for removal” An email has been sent to your “Emal ID”. Click the link in this email to confirm the removal of your account.
4. Finally after confirming the Email you are done.