It has been a legal requirement in the UK that databases must be able to delete personal data since the data protection act 1984 - https://www.legislation.gov.uk/ukpga/1984/35/enacted - in particular see the data protection principles in schedule 1: the 6th principle requires that data is retained no longer than necessary. There are provisions elsewhere in the act that can require a data holder to delete data.

Most of GDPR is not really new. There was a significant amount of teaching about data protection when I was at university in 1994-1997 and it wasn’t even new then.