Doubt related with windows service

hi all

I have one service i installed same in another system which was working well
after a few days i tried to uninstall windows service using command which i successfully used before c:..../installutil /u myservice.exe
showing installutil is not recognized as an internal or external command
why showing this ??
I googled alot for this issue but cant findout a solution
Can Anybody suggest solution for this


Thanks in Advance
Amrutha