You don't. Cross save doesn't transfer data between accounts. With cross save enabled you are playing your PSN characters and game progress on Steam. The entire time you're still technically a PSN account even though you're playing on Steam. This is also why when you look up anything related to your account you get your PSN information because you are currently playing PSN characters and game progress. If you disable cross save your Steam account will only have access to the characters and game progress earned on that account prior to you enabling cross save. Which means you'll be going back to 3 characters with roughly 5 hours of game time. You current PSN characters and game progress will then be only accessible when logging into D2 on a PS4 or PS5 if you disable cross save.