Determine whether document is synced or not

I am developing a mobile application which is intended to sync with couchbase server. In application level there is needed to create an audit document for creation, update of document. In Audit log scenario I am using only push replicator to sync with couchbase server. After syncing documents with couchbase server I want to delete synced documents in audit bucket only from couchbase lite (not from couchbase server). Is there a way to determine whether document is synced or not.
If there are a way to purge all synced document by invoking a method at once, mention it in this post.
sync gateway version 2.0

Android mobile SDK

Thanks…!