need help deleting samples

whats up pplz, i just got my mpc 500 and it shipped with a 4gb memory card. The card already had a bunch of samples n shit on it but ofc i want to get rid of em and put my own samples there instead. So i plug the mpc via usb to the computer and i delete all samples, but when i plug it out and want start sampling i notice that all the samples are still there, and im in wtf mode. Are the samples stored in the internal memory or something?
peace

Here you go, straight out the horses ass.

MPC500 options:
Formatting the CF Card:
1. MODE+SAVE[PAD 3]
2. Scroll the wheel all the way to the right.
3. Press 12 LEVELS/DO IT, you're done.

Deleting everything off the Internal memory:
1. MODE+SAVE[PAD 3]
2. Scroll the wheel 6 steps to the right, it should say
"SAVE:To internal/All sq&song|pg&smpl"
3. Press 12 LEVELS/DO IT twice.
4. Something will pop up saying "Replace memory/Press REC bttn", press the REC/Record button.
5. When it's done erasing the flash at 100% TURN THE MACHINE OFF ASAP!, then you're done.

Connecting the CF card reader on your MPC500 to the PC:
1. MODE+SAVE[PAD 3]
2. Scroll the wheel 2 steps to the right until it says [USB :] on the screen.
3. If you have your USB cord connected to the MPC and PC it will open up a new drive displayed in My Computer. Done.

Purging/deleting samples you didn't enable on any pads off your CF card:
1. MODE+PROGRAM[PAD 6]
2. Scroll the wheel all the way to the right.
3. It will say "Purge unused/Press DO IT"
4. Press 12 LEVELS/DO IT. You're done.

thanks bro!