If the installed program is a recent version, simply by using the Add / Remove programs from the Windows Control Panel. But if the program is a older version, you have to use the removal tool from the original CD.
Note for Mr.CAD SA and Mr.CAD Professional v.7 or greater: If you don’t have plans of re-install the program on the same PC, before remove the license activation. Removing the program installation, does not deactivate the license. See article: How to remove my license from my PC