Using older versions of Outlook for Mac for personal email and calendar
Yes, if you need delete those email, you may contact those group owners or admins to add you as a owner groups to delete. Only group owners could delete mails.
If you delete it, the remaining of your group members will not see this message any more.
We hope this answer your questions.
To add you as group owner, for you admin reference at the admin center:
Kind Regards,
George