The directory where MusiCAD was installed to (default
C:\Program Files\Musys Software\) contains a removal program
The removal program will ask for confirmation before actually de-install MusiCAD from your computer (Windows UAC will also ask confirmation on Vista and Windows7).
The usual way of de-installation is by means of the standard windows installation/de-installation program to be found in windows configuration screen, just like most other programs you wish to remove which will call the removal program above.
Please see https://support.microsoft.com/kb/307895 for detailed information.
Simply removing the MusiCAD directory and icons will not do much harm, but will leave some clutter.