The RmDir command can delete a directory only if it doesn't contain files or sub-directories. If the directory you want to delete does contain other files or, worse, subdirectories it seems that you are forced to use a recursive routine that does the job.
A simpler solution is offered by the DeleteFolder method of the FileSystemObject object, exposed by the Microsoft Scripting Runtime library:
You can also pass a second argument and set it to True if you want to force the deletion of read-only files:
' NOTE: this code requires that you add a reference to the
' Microsoft Scripting Runtime type library
' delete the C:\TEMP directory and all its sub-directories
Dim fso As New Scripting.FileSystemObject
fso.DeleteFolder "c:\temp", True