Wrong link here in your comment but thank you very much for helping me find the correct issue. Should be:
https://bugs.mojang.com/browse/MCL-11440
Instead of:
https://bugs.mojang.com/browse/MC-11440
Thanks!
This isn't resolved. This is just REALLY annoying. Fix this.
You can't delete them. In addition, you can't rename them. In addition, after a second launch of the launcher you get this:
"<unnamed installation>"
You cannot correct this through the launcher's UI. The only recourse is to go edit the json file. Please fix. Extremely aggravating.