Wow, you really are aggressive and hostile for no reason. You can use Ubuntu all you want. But don’t go around spreading lies just because you are too cognitively challenged to change your DE without breaking the OS. Most people are fine making a fresh install with the DE they want to try preinstalled and it works fine 100% out of the box. It’s trying to make two different DE live on the same system at the same time that is only partially supported and thoroughly discouraged by every single DE developer. Most of the time installing a new DE on a system and uninstalling the old one is a pretty straightforward, although dirty process. Guess who is particularly bad and incompatible with that process? Ubuntu. It has the worst support for alternative DEs, because Ubuntu is not the benchmark for squat shit anymore. Use a real end user distro, and you’ll be able to change DE to your heart’s content without issue.