title: Single git command to bulk delete unsued branches
body: <p>I am just  looking for  a git command to  bulk delete  my unused  remote branches.</p>
  
  <p>My requirement is like , i want to delete a merged or unused branches for a particular user for past months.Lets say, A is an user created 10 branches on november and also he created 10 branches on december. Now he wants to delete november branches.</p>
  
  <p>I just  tried with git  for-each-ref for that : </p>
  
  <pre><code>git for-each-ref --format='%(committerdate) %09 %(authorname) %09 % \ 
  (refname)%09 %(committerdate:relative)' --sort=committerdate  |grep "Rk"
  </code></pre>
  
  <p>Any solutions would be appreciable</p>