The syntax is simple are only two switches:
/S = also remove all sub-directories
/Q = Quiet / Silent / do not prompt user to confirm deletion
The following command will remove the McAfee folder AND everything under it.
rmdir /s /q "c:\Program Files\McAfee\"
There is no requirement to put the path in quotes unless you have long file names, but the quotes do not cause a problem so I use them on all rmdir commands
If files are in use, the command will complete successfully but leave those in use files / folders in place.
Alternately, if RMDIR is just too many letters for you to type Microsoft has added an alias for this command. You could just use RD in place of RMDIR.