Delete email from user mailbox exchange powershell

To Identify the number of messages with search criteria
Search-Mailbox  -Identity myendusername -SearchQuery '(Subject:"confidential info") AND (received>10/20/2019)' -EstimateResultOnly


Move messages to temporary mailbox for review if the you will be deleting exact messages.
Search-Mailbox -Identity myendusername -SearchQuery '(Subject:"Confidential Info") AND (received>10/20/2019)' -TargetMailbox test1165 -TargetFolder MyEndUserMailboxfolder

Delete the messages from mailbox
Search-Mailbox -Identity myendusername -SearchQuery '(Subject:"Confidential Info") AND (received>10/20/2019)' -DeleteContent

Note: put below after search-mailbox if required.

-resultsize unlimited