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
- Naming the policy (mandatory) and a description (optional)
- Then set your policy settings; you can use predefined configuration or create a custom one
- Set the content location – by default all location (except Skype for Business) are enabled; targeting either all mailboxes, all SharePoint or One Drive site or all Office 365 Groups. This means you can set different policy depending of the Office 365 Groups usage (private, public…)
- Finally turn on or off the preservation lock which basically will lock policy deletion
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.