Hi lhc
If you click on “purge” it will remove all files that are no longer on your computer. then click “lookup” and it will check if the files are on the Comodo safe list. If they are they will come back labeled “safe” and will be removed automatically. The rest can then be sent to Comodo for inclusion in the safe list. Just leave them pending for the time being until they are labeled safe or you can move them to your safe list yourself if you are certain that they are safe.
Hope this is a bit of help for you
John