this site collection can't be deleted because it contains eDiscovery hold or retention policy

I applied O365 group retention policy about 3 or 4 months ago.  After I deleted some of O365 groups, it deleted O365 groups, but it left SharePoint sites associated with O365 groups. 

When I run Remove-SPOSite command, I get "This site collection can't be deleted because it contains sites that are included in an eDiscovery hold or retention policy".

I tried to exclude those O365 groups from retention policy, however since I deleted groups, I can't find deleted O365 groups to exclude from retention policy.

Is there anyway to remove sites from retention policy and remove these sites? 

Thank you.

Akiko