how to get rid off abandoned cop-files in cache folder?

hi, i just have realised, my "small" 75.000 photo catalog, has a huge cache file folder with some abandoned cop-files. just changed the preview size to 640px and started to regenerate new previews in hope the catalog’s cache will be much smaller. as I've seen there are some cop-files inside which don't have the correct names.

my activities panel shows me a i only regenerate 24.000 previews form a selected folder with 49.000 photos. in my cache folder i have 11.000 cop-files with a wrong name.

can i delete them, or how can i get rid of them?