Hi,
After reading a few posts...nobody has suggested the obvious solution..... simply delete them all...and dont forget to "empty" Recycle Bin ..or he can simply restore them.
How to delete: open the folder holding the pictures - click one to select it.
In the top menu..select EDIT...at the botton select SELECT ALL
On the left in that panel is a Red cross..double click to delete all.
OR if no side panel, Right Click the mouse button and select DELETE.
Double click RECYCLE BIN, Select FILE in top right menu bar, select EMPTY RECYCLE BIN.
Job done ..now sit back and smile!