title: Find and remove all documents whose "createdDate" is one month older
body: <p>I am working on <code>MongoDB Collections</code>. I have a set of collections each having many documents. I have to write a procedure to delete all those documents whose "createdDate" is older than one month from current date.</p>
  
  <p>I am stuck in finding the date which is one month back of the current date in order to compare it with document's "createdDate".</p>
  
  <p>Also i have to schedule this procedure, so that it can run automatically everyday. (OS is windows). How can i achieve it?</p>