IMO, the easiest way to install rEFInd on a preinstalled system is to use Manjaro Architect LiveISO. Though you can use any LiveISO and launch Manjaro Architect within it.
NOTE: These are older images, but the layout is the same.
Once you get into Manjaro Architect:
- Go to Prepare Installation
- Go to Mount Partitions
2a. It should ask you to mount/and also/boot/efiat the end
-
From the same image above, go to Back
-
You’ll be back at this screen, and go to System Rescue
-
Go to Install Bootloader
-
Install refind
And you should be done.
I don’t know the correct way to remove grub though. I just install my whole system with Architect typically, and select refind as my bootloader to install. Just make refind your top priority for boot in your BIOS, though it should automatically do it from this installation in my experience.
Self plug of my refind theme if you’re interested. Don’t use the theme until you know refind is working.
https://archived.forum.manjaro.org/t/refind-sunset-theme/38078