Case 1: Your replication queue is blocking and you have no idea why it is not getting processed.
Case 2: Some one accidentally activated thousands of pages and you want to clean them now.
Case 3: You want safe way to remove replication jobs and then activate them again if required
Case 4: You want to clean a dummy or problematic replication agent
Pre requisite : CQ5.4 or CQ5.3 with replication fix pack.
1) Install attached package using package manager
2) Go to http://<host>:<port>/apps/tools/components/cleanReplication/run.html Or go to http://<host>:<port>/etc/replication/agents.author.html click on your agent and you will will have options.
3) First do dry run and see if entries are getting deleted
4) Then check all checkbox and click on run clean replication.
5) There is also a failed replication Listener configuration, You can configure it to send an email in case replication fails.
Here are some screen shot