When you post your lift, a email was sent to you with instructions and an link to change your listing. Search your inbox for an email with the subject "UPDATE/DELETE your lift from A to B".
Follow the link in the email, this takes you to the post your lift page where you can edit all the details of your existing lift, or remove it from the site. If you cannot find the email, please check your spam folder, and add no-reply to your address book to make sure your email client won't hide it in the future.