Recently 'delete handler' was added in jackrabbit. This provides the ability to add handlers for handling webdav based 'delete' requests. See
JCR-3884 containing details on this feature. Earlier this ability was just available for other webdav operations like to copy/move etc. but was missing for 'delete' .
Sling has written its own managers to keep track of these handlers. See  which has pre-existing handler managers like SlingCopyMoveManager.
The intent of this jira issue is to add a delete handler manager so that the delete handler functionality can now be leveraged in Sling.