Check that the VST Audio Engine has quit before relaunching Dorico. (Use Activity Monitor to find and quit the process.) Or reboot.
Try reinstalling once. If that doesn’t work, then you know the problem isn’t going to be fixed by reinstalling again.
The Mac’s OS is on a read-only volume, and won’t boot if it’s been modified. There is therefore no need to wipe and reinstall the OS.
Usually, problems are caused by: corrupt user configuration files, incompatibilities of old software with the current OS; or things you’ve forgotten about that are running in the background, and set to start up every login.