My son told me they go to some unused space and disappear when that space is refilled.
Something like that, I am no expert. A forensic computer expert could find it quickly. They are still on the hard drive somewhere.
When you delete a file off of your computer you are essentially deleting the record of its location on the hard drive and not the file itself. The computer then can use that space to write to.
There is all kinds of software that can recover that, I am doing that now on an external drive that got corrupted which looked like it erased 500GB worth of pictures and video of the kids.