After Import - Erase Images after Copying from filesystem too

I often copy images off of my memory cards or camera to my local filesystem before I can run the import tool so I can use my cards/camera again, it seems the option for erasing the images that were imported after importing are unavailable when importing from the local file system. I typically wait to use the import tool so I can use the features built into it like the grouping, face focus viewer, and updating metadata. Without erasing them after an import this makes the import tool have to crunch through thousands of images in between each import where I am usually having to go back and filter by month to import in batches. If importing from either a card or file system I should be able to choose if I want to remove the images that were imported or not by checking the box. The folder i'm importing from is just on my desktop and I have full read/write permissions to the location.