@Bharath N, you don't need to purge edit log files. HDFS deletes them automatically when they are no longer needed. I recommend not touching any edit log files since accidentally deleting the wrong file could lead to data loss.
For your NameNode start problem, I can't say anything without more data. You want to engage Hortonworks support for this problem, if you have a support contract. Else you can post the error message/exception here and we may be able to point you in the right direction.