You can now set a retention policy on Office 365 Groups to comply with your retention policies; as you can already do it on Exchange mailboxes or SharePoint sites.
NOTE it can take up to 1 day to get the policy applied
To set a retention policy on Office 365 Groups, logon to the Security and Compliance administration portal – either from the Office 365 Administration portal from the Admin Centers shortcut or using the URL https://protection.office.com
Then go to the Data governance\Retention section and create a new policy (or update the existing ones if you want); I would recommend to have retention policy for each workload individually but it depends on your context
Then follow the policy creation wizard by
From there your Office 365 Groups (existing and new [if you choose to apply to all groups]) will automatically get the retention policy applied and you will be able to get reports and/or recover content.
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