How to delete files on GL-AR750?

I’m not sure how it happened, but there are some photos and other files that got saved directly to the router. There is no SD card or hard drive plugged into the device. I’m trying to delete these files, but it says permission denied. How can I delete these files?

Which folder do these files saved? Can you give a screenshot?

Ok, the information was still showing in a folder (partition?) named sd1b, which must’ve been on the SD card that I had plugged in, and after I removed it, it was still showing the file names. I rebooted the router and the file names are gone now.

When you remove the sd card, it is not unmounted. So the names are still there but file is not actually gone.