Finding and deleting specific email or emails across mailboxes in an Office 365 Organization.

You can use powershell and the security and compliance functions within Office 365 to search for and delete a mail across multiple mailboxes within Office 365.

This MS Office 365 Admin Help article shows you how:

https://support.office.com/en-us/article/search-for-and-delete-email-messages-in-your-office-365-organization-admin-help-3526fd06-b45f-445b-aed4-5ebd37b3762a#step2