You can archive your screener but cannot delete it completely. To do this, go to your screener dashboard (Screeners>>Overview), click the three dots and "Archive."
This will remove that particular screener from the screener overview. You can always bring back an archived screener by clicking on "Archived Screeners" on the left and selecting the screener that you want restore.
If you are archiving a screener, be sure to take the ethnio code off of any sites! Otherwise you'll still be incurring pageviews.
Note: for links, if you archive a screener it will automatically turn the screener off. So be sure your project is completely finished before deleting/archiving.