If you want to delete a specific contact list, you can choose it in two ways.
Click "Delete" next to a chosen contact list on the CONTACT LISTS OVERVIEW page.
Click on the chosen contact list name and then click the "Delete" button on the CONTACT LIST'S DETAIL page.
When clicking the "Delete" button, the enquiry to confirm will be displayed. When the operation is approved, click the 'OK' button. Otherwise click 'Cancel' to discard operation. Both buttons are located in the pop-up window.
Video Manual. Deleting Contact list
If you want to delete a specific contact list, you can choose it in two ways. 
Click "Delete" next to a chosen contact list on the CONTACT LISTS OVERVIEW page.
When clicking the "Delete" button, the enquiry to confirm will be displayed. When the operation is approved, click the 'OK' button. Otherwise click 'Cancel' to discard operation. Both buttons are located in the pop-up window.