You can perform a search and the pipe to delete ( | delete). That will delete that specific data from being searchable. In your case you could specify a certain source and host to target an individual log file source. It does not however reclaim disk space. The only way to do that is to clean the index. Note that there isn't a role that has access to delete by default and as a best practice you should not give that access anyways. So, you'll want to temporarily give access and then take it off afterward.