Step 1: Press the gear icon.
Step 2: Scroll to SYSTEM > USB MASS STORAGE MODE and press the encoder.
Step 3: Confirm.
Step 4: Connect USB to your computer.
Step 5: Open the NO NAME device.
Step 6: Open the PIONEER DJ SAMPLER\SAMPLES\SAVED folder. Navigate the folders files within (projects) and samples within them, delete or copy as needed.
I'm sorry this isn't available directly on the unit itself, but it's not terribly difficult to manage them this way.