Hi Ankit,
To do impact analysis, you can use Query Builder.
Try below queries:
SELECT * FROM CI_INFOOBJECTS, CI_SYSTEMOBJECTS, CI_APPOBJECTS
WHERE PARENTS("SI_NAME='WEBI-UNIVERSE'","SI_NAME =’<universe_name>’")
Provide the universe name in the above query and it will give you the list of reports which are using that universe.
You can then edit the reports manually in order to find out if that particular object is used.
As far as I know as of now, there is no direct way to check if an universe object is present inside a report directly though we can find the universe linked with the reports.
The below blog can help you further:
http://scn.sap.com/community/bi-platform/blog/2012/10/11/businessobjects-query-builder-queries
Regards,
Yuvraj