Can't delete pictures from Galaxy S9 plus SD card via USB

My Galaxy S9 plus recognizes and uses it's SD card which I had used and transferred from my Note 4, I can see all my JPGs and can delete from the phone without a problem. So the card apparently works, . When I connect the phone to my computer via USB-C, I can see the phone and the card and all the JPGs on them in Explorer  but I can't delete any of them from the card. I experimented by trying to copy a JPG from the computer to the card and and was then able to delete it, but I can't delete pictures that were already on the card from the old phone. Again, I know I can do that from the phone, but I have tons of JPG files on the card which I was hoping I can of bulk delete from the computer. Any thoughts? Thanks