removing the 'title' field from custom content types
You are looking for Exclude Node Title module


  This module handles a very simple functionality, decide whatever to
  exclude a node title from full node page or node teasers. It provides
  a checkbox on node-edit pages for easier exclusion, or you can use the
  admin page to manually enter a list of node id's to exclude title.


Also provides the option to hide all titles of a certain Content type.