How to know who deleted folder from Power BI Report server

PBIRS does not have anything like a "recycle bin" so there is no way to know who deleted something. The only way to recover this is to restore the entire ReportServer database. You probably want to do this on a different server (not your production box) then copy out the files and re-upload them to your production server.

Regarding the "Who deleted" - depending on how much you would like to interfere with the server, I could think of a couple of solutions if this happens on a regular basis.

• You could somehow create a monitoring system were you save the current state of the [dbo].[catalog] table and then you can check the executionlog (https://docs.microsoft.com/en-us/sql/reporting-services/report-server/report-server-executionlog-and-the-executionlog3-view?view=sql-server-ver16) to see which users where using reports at that time.
• Also maybe use extended events to log user actions. I think deleting a folder somewhat results in a query