@CloeW938  There are Pega Case Purge configuration you can try but I do believe there is nothing to automatically delete/purge Work or Case Data on Pega Managed Cloud Servers unless the Customer configures the Case Purge utility to do so. It is customers responsibility to look at Case archiving and purging overview | Pega and set up their own purging and archiving needs, pega Managed Cloud instance would not automatically clean up anything I believe.

Regarding backup for Pega Cloud Servers to be decommissioned - You can have Pega BIX to extract all Case Related Data, (better to target all attributes that matter to you, as there can be loads of Pega Internal Attributes, audit, SLA, etc.) into XML or CSV and then hold it on your Organization location i.e. outside Pega Cloud, you can use SFTP to do so.