I agree with Frostj, We’re hopeful this is just the first new feature Google will introduce to help marketers control how customer data is stored and for how long. This isn’t a catchall solution for GDPR compliance, but it’s an important component.
To find the data retention controls simply navigate to Admin –> Property –> Tracking Info –> Data Retention. Currently, Google offers two options in the Data Retention Controls. These settings won’t go into effect until May 25, 2018, but there’s no reason to delay.