How to cleanup the Recoverable Items in the cloud and On-Premises
We have recently published two articles to help cleanup recoverable items when a mailbox is placed on In-Place Hold or Litigation Hold or has single item recovery enabled, you'll want to preserve the mailbox data until the hold is removed or single item recovery is disabled. In this case, you need to perform more detailed steps to clean up the Recoverable Items folder.
The detailed steps are located here:
On-Premises: Clean up or delete items from the Recoverable Items folder