There is an easy way to erase your MBR in Linux, using the 'dd' command. The following steps should not be taken lightly, and you should always have a backup of your data before attempting such things!
dd if=/dev/zero of=/dev/sda bs=446 count=1
... where /dev/sda is the drive you want to remove the MBR from.
Note the blocksize of 446 is supposed to erase everything up to your partition table, but not your partition table itself.
dd if=/dev/zero of=/dev/sda bs=512 count=1
... where /dev/sda is the drive you want to remove the MBR & partition table from.