You don't have to uninstall and reinstall anything.
It's in situations like these, that you can see the benefit of installing FSDT into their own folder, with just a link to the Community folder, because now you can install MSFS 2024, start the FSDT Installer again, select MSFS 2024 (if you keep 2020 installed, you'll see a choice) and click RELINK, that's it.
Of course, if you see there are updates available for the sceneries, be sure you apply them, since the latest updates that came around a few days after 2024, were required to fix any compatibility issues with it. You can perform the updates before or after installing 2024, it doesn't matter.
