Deleted workspaces aren't recoverable, chances are that this scheduled report still exists in the scheduled reports section.
Components> Scheduled Reports
Search here and see if you can find it and delete it.
If you cannot find it, open a ticket with client care.
clientcare@adobe.com,
Please include:
Company:
Schedule Report Name:
Report Suite:
and any other information.
Thanks,
Steven Hofheins | Adobe Support