You can select groups of contacts and delete them in one click:
1. Click on your website's icon on the left-side of the screen to view the menu bar. From there, go to "Contacts".
2. Choose the list of contacts you want to delete through the Filter by menu.
3. Check the box next to each contact that you want to delete or the Select all option if you want to delete all the contacts in the list.
4. In the upper bar, click the red "Remove" button.