I never heard of this word rsh and also received a check list from Security pro that we have to disable rsh.

Can someone please tell me what is this rsh and how to disable it.

Base OS : RHEL 5.5 and 5.6

-
Had a look at what Wikipedia proposes "Rsh" might be? Remote Shell sounds like something a security pro might advise you to disable... I don't know RHEL, but maybe editing /etc/xinetd.d/rsh is a solution (look for disable). –  sr_ Jan 12 '13 at 10:27

I don't know which OS you are talking about, but for RHEL (like sr_ already stated) edit /etc/xinetd.d/rsh and set disable = yes.
After that restart xinetd and you're done.