You don't need to delete the App store version. Because it's sandboxed, it does not conflict with with the BMD version. But if you wanted to delete it, you'd just delete the DaVinci Resolve Studio.app or the DaVinci Resolve.app file from the Applications folder. Those are the App store versions.
The BMD version creates a DaVinci Resolve FOLDER in Applications, and lives in that folder.
But I would suggest just leaving the App store version. Because...
The Resolve project data for the App store version, because it's sandboxed, does NOT show up in the BMD version. You would want to do a database Backup from the App Store version and Restore that backup into the BMD version, as the easiest way to get all your projects copied over. Or, if you just had a few projects you cared about, you could make project export .drp files in the App store version and Import those into the BMD version.
The downloads for all Resolve versions from 10.1.5 to the most current 16.3b3, all live on the BMD Support page, in the DaVinci Resolve area:
https://www.blackmagicdesign.com/suppor ... and-fusionThe versions labeled Studio are the paid versions that require a license. Either a dongle or activation code.
The versions without Studio in the name, are the free versions.
Apple doesn't have their own version. We have placed Resolve on the App Store.