Probably don't have it in your path...
Few options:
1) Type the full path: "C:\Program Files\Windows Resource Kits\Tools\delprof.exe"
2) Set temporary path:
From a command prompt, type
set path=%path%;:C:\Program Files\Windows Resource Kits\Tools"
3) Set a permanent path - Start->Run->sysdm.cpl
From the Advanced tab, environment variables, extend the path varaiable as outlined in step2 (put a ; on the end of the current path...