To delete photos on your datalogixx, you will go into your MO disk app with your datalogixx 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 are able to see the images you want to delete, you can hold down 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 from your datalogixx.
ou 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)
If you want to delete only one photo, follow the same steps as above but only select the image you wish to delete. Here, the trash button will be at the top right of the screen to delete the photo.