Data should never be actually deleted from the database, that breaks all the best practices. It can be overwritten with garbage though. But it should always be present.
For example, if you create a new account with email, username and password and get assigned some id like 42. Then after a while you want to delete your account. The account should stay intact, id number 42 should still be occupied, but your email, username and password should be replaced by null values.
Data should never be actually deleted from the database, that breaks all the best practices. It can be overwritten with garbage though. But it should always be present.
For example, if you create a new account with email, username and password and get assigned some id like 42. Then after a while you want to delete your account. The account should stay intact, id number 42 should still be occupied, but your email, username and password should be replaced by null values.
Reference avro schema changes