title: Zero-fill Android device internal memory
body: <p>After taking backup of Contacts and other information. I want to zerofill the internal memory (In order to wipe-out the data completely). The device is 'rooted'. But, little confused on where to start &amp; how to start. Can somebody provide some information with code snippets to do it.</p>
  
  <p>The memory is where data is stored should be reset with zeros.</p>