To delete specific photos on your Clickfree, you will go into your Clickfree app with your Clickfree plugged into your phone.
Once the app is opened, you can click on "VIEW BACKUP STORAGE" from the main screen of the app (and you'll most likely want the backup folder after selecting the "VIEW BACKUP STORAGE"). Click on whatever folder you will be deleting images from. Once you have found the images you want to delete, you can hold down on one image for a few seconds and select multiple photos. Then you will hit the delete button at the bottom of the screen. This should delete the file(s) from your Clickfree device.
You can also slide your finger from the right to the left on a specific picture you would like to delete, and a red delete button will appear on that picture's description space. (As in the rectangle that each photo has)
You do this for contacts in the same way: be in "view backup storage" and your contacts folder."
If you want to delete all of them, then you would choose the menu option at the top left of the screen (three horizontal lines).
From there choose format, choose the CLICKFREE (FAT32) option using the little bubble, click format at the bottom, choose OK. Everything will then be deleted.