Thanks Dave,

I was able to clear the table umbracolog

delete FROM umbracolog WHERE Datestamp < DATEADD(day, -1, GETDATE())    

Also, umbracoContentVersion & umbracoDocumentVersion

SELECT cv.id
INTO #toDelete
FROM umbracoDocumentVersion dv
INNER JOIN umbracoContentVersion cv ON dv.id = cv.id
WHERE cv.[current] != 1 AND dv.published != 1 AND cv.VersionDate < DATEADD(day, -1, GETDATE()) 
DELETE FROM umbracoPropertyData WHERE versionId IN (select id from #toDelete)
DELETE FROM umbracoDocumentVersion WHERE id IN (select id from #toDelete)
DELETE FROM umbracoContentVersion WHERE id IN (select id from #toDelete) 
DROP TABLE #toDelete

But the mentioned table umbracoAudit remains untouched. Now I have truncated that one and the site working without any issues.

Is there any suggestions that will be helpful to reduce the DB size further?

Thanks