(1) Click Terminal
(2) Become root by command
when root password demanded just press return.
(3) Check the partition layout by command
The Xp partition has an ID type no. 7 for NTFS filing system.
(4) Fire up command
and use it to delete anything you don't want, click "write", confirm with "yes" before exit.
(5) recheck the partition table with
(6) If you want it bomb proof, just do a reboot.
Advice - There is no necessity to nuke a Xp partition. Resize it and use the squeezed out space to install OpenSuse is a smarter move. Xp has a license and that should come in handy. 10Gb is big enough for a Suse Linux.