- connect your idevice
- open preview
- select File > Import from (your Idevice name)
- then select all and choose the red circular symbol at the bottom
- this will delete all your photos and videos in one go
- connect idevice
- open My Computer
- find your connected iDevice..open it
- go through to view all pics and vids
- select all and then delete.
- this will delete all in one go.