There are multiple ways you can this. The first way is to connect the photo frame device to your computer. When connected, the device will be detected as several devices with removable storage. One of these devices will be the on-board memory. You can then double click this device and then delete the files that you no longer require. The second way is to use the delete option on the photo frame -

1. Select your memory source, either the on-board memory or an inserted memory card, then press the enter button on the remote

2. Select 'Edit'; this will display the files located on the memory source

3. Select the file or files that you want to delete by pressing the right arrow button on the remote; you will see a tick icon next to each file that you have selected

4. Press the MENU button on the remote, then select delete; confirm your selection then press the enter button on the remote

5. The file or files will now be deleted from the memory source