Ok, first you explaine what do you want to do ?
How do you mean "to format rh" ?
Do you simple want to delete this partition or prepare it clean for installation of linux ?
Anyway, through installation process of every linux distribution, there is tool (step) for manipulating disk and partition. So, here you can format, delete ... your rh ... Or you can use Partition Magic program for Windows ...
I sopose that you know that you have to make / (native) and swap partition.
As I see, you dont know what is slackware (
http://www.slackware.com), and dont know what is distribution ? My suggest to you is to first read some basic documentation about linux and unix. In that aim visit
http://www.linuxdoc.org where you have online documentation, and also you can download docs in different kind of formats (html, ps, pdf ...).
So, READ !!! :-)