I'm on my laptop which is rather old, but I'm just downloading godot to check the project manager, should be capable enough for that. But IIRC you should be able to remove projects from the list one by one, by right clicking on the item in the list and removing it.
edit: on the side theres a button to remove a project, thats what it was.
I do agree that a system for selecting multiple projects via option/tick boxes and then removing or editing a limited subset of the common project settings would be nice though.
Probably worth making a feature request for it, but I'd have to take some time making up some example images and properly thinking through how the UI &UX should work first.
edit 2: Ah, @TwistedTwigleg s post already links to a screenshot of the updated design for 3.2. Looks like a good start.