Wiping is easy. Reformat the HD.

Better approach:
1) get the Linux install package (download and burn to CD or go
buy one at your local computer store, usually about $20-50).
2) MAKE SURE the CD (and/or floppy if needed) is an install disk!
3) change the bios to boot from CD or floppy first, then HD
4) have fun!

If you've never installed linux/unix before, spend a lot of time
reading and understanding what you're about to do.

And make sure your hardware is viable for unix/linux