It's a bit dangerous for users giving advice here for someone to delete something. Having said that disclaimer, I think the answer depends on how you installed version 2019.

If you have ANY uncertainty about what you are doing, I suggest you contact PG Music Support and run it by them.

In theory, yes, you can delete the 2018 installation on your internal hard drive by just deleting the /BB folder. First you would want to save any of your songs or styles. You would also want to make sure you have the installation files for any Bonus Paks you may have bought. Also, if you think you might ever want to install the 2018 version again, then first deactivate it.

If you installed 2019 by using the minimal install, then the files you need to run from the external drive are loaded onto your laptop, and you can delete the 2018 /BB folder.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.