I’m using Ubuntu Studio 24.04. It has Ardour 8.4.0~ds1 (rev 8.4.0~ds1-2ubuntu8) installed.
I am considering filing a bug report but I want to try the problem on the latest version of Ardour first. So, I’d like to install the latest version for a temporary test but I don’t want to install over the existing version.
Official builds go into /opt/Ardour-version
There should be a script file with name /opt/Ardour-version.uninstall.sh
In release builds version is just the number, like 8.10 for the latest, so I think for the nightly it should probably be 9.0.pre0.711. Not sure if “demo” is part of the file name or not, you will have to look in the /opt directory and verify.
Run that script and it will remove the version of Ardour.
You can install multiple versions of the official builds, each goes into a separate directory in /opt.