Linux Delete / Remove MBR

You can delete the mbr (master boot recored) using the dd command itself. The following command will completely delete your MBR, which contains all your partition information. So make sure you use the correct device name:
# dd if=/dev/zero of=/dev/sdc bs=512 count=1
Sample outputs:

1+0 records in
1+0 records out
512 bytes (512 B) copied, 0.00308483 s, 166 kB/s

/dev/sdc is your USB pen device.