If you have not yet sent an email or test email to the list, you can replace the file by clicking Email > Lists, and then clicking the pencil icon next to this list. You will see a Replace This File button.

If you have already sent a message or test email to this list, you will not be able to edit or replace this list. If your imported recipient list requires changes, You will need to create a new email list in NetCommunity and re-import the updated .CSV file..