Backup is important but, can be dangerous when we cannot track and delete old data. This is where "Cryptographic Erasure" can be useful. It is a simple process, you encrypt the data and when it is time to delete it, DELETE THE ENCRYPTION KEY INSTEAD . Data is as good as deleted.

It has two important advantages:
1. We do not need to restrict ourselves to using a single key that encrypts an entire drive or data set. Instead, we can have as many unique keys as we need, encrypting data at the granularity that serves our purposes

2. Second,it entirely bypasses the issue of tracking data flows. Whether the data resides in a remote data center, in someone else's cloud, is irrelevant. It is sufficient to know where our keys and delete them.

https://www.darkreading.com/endpoint/cryptographic-erasure-moving-beyond-hard-drive-destruction/a/d-id/1333492