Easiest way to insert contacts via the list is to:
Go into a settings icon (gear icon)
select option import contacts from a list
This option will add contacts to the list.
When creating a list, there is a checkbox that reads: Make this list available in the Contact Manager. If you want your list to be available inside the contact manager, then select this option.
There is multiple ways to remove contacts from the list.
Depending on the contacts you want to remove you can choose one of the following steps:
If you need to remove just a few contacts, best way to do it is to go to the list and in action column remove the lead from the list.
If you need to remove all contacts from the list, then click on a gear icon in your selected list, and select Clear All Contacts from List
On options icon, you will have more options to delete different type of contacts.
Clear Unsubscribes
Clear Hard Bounce