In my opinion the Carbon-based version is not a good long-term solution anyways so personally I'd uninstall it, yes.
I don't think there's a "special" way to do it that would be any different from how you'd normally uninstall something you got through a DMG file.
Again also, I would definitely recommend FPCUpDeluxe, yeah.
The two relevant FPCUpDeluxe download link options for x86_64 Mac are:
The native Cocoa-widgetset-based version:
https://github.com/LongDirtyAnimAlf/fpcupdeluxe/releases/download/1.6.2h/fpcupdeluxe-x86_64-darwin-cocoa.zipor the QT5-widgetset-based version, which uses Cocoa indirectly:
https://github.com/LongDirtyAnimAlf/fpcupdeluxe/releases/download/1.6.2h/fpcupdeluxe-x86_64-darwin-qt5.zipI'd highly recommend trying the normal Cocoa one first, as it will build a native Cocoa-based Lazarus by default. Only if it gives you problems, which hopefully it won't, should you try the QT5 one I'd say.
Note that the Cocoa widgetset has been getting a
lot of work done on it recently and has to my knowledge been improving steadily, so it will possibly be a better idea to choose the "trunk" branch for Lazarus in FPCUpDeluxe.
I've attached a screenshot I took (on Windows, but it's the same application) of what it looks like with trunk FPC and trunk Lazarus selected in FPCUpDeluxe right before clicking the button to download/build/install them (which is the one labeled "Install/update FPC + Laz".)