rmdir won't remove a non-empty directory unless /s is specified:
c:\> rdmir /s p:\ath\of\non\empty\directory
p:\ath\of\non\empty\directory, Are you sure (Y/N)?
In order to prevent the Are you sure (Y/N) question, the /q (quiet) flag needs also to be specified. This is especially useful in batch files because this question stops the execution from proceeding.