OK. Searched online and here. For a long time.

Since I got back into Linux a few months ago, I was trying to get a Windows program I use to work in Wine. Over three HDDs, one SSD, two regular HDDs, ZI have put in

1. Feren OS
2. Mint
3. Manjaro
4. Ubuntu

How do I find which one is where? I want to delete all but Ubuntu but, when I am in any one, how do I find out where it is installed to? All I see is "bin boot dev etc home" in any file manager, gparted, etc. in each HDD. I want to delete, clear a bunch of space and stick to Ubuntu, but I have no idea what is where. It is all just ext4 partitions. Is there a way?

Thanks,
Zukester

Mount them and check what’s in /etc/os-release.

Boot up Ubuntu and look at the output of the command lsblk -f

match the UUIDs in the fstab file with the output and everything else are the others. Do you have any swap partitions? Are you using MBR or gpt/uefi?

boot-repair and its ilk will tell you most of what you want to know.

Boot each one and note output from df /. Match these outputs without output from lsblk -f to match the device names to the UUIDs. The one matching your Ubuntu / contains the /etc/fstab with entries for the filesystems you need to keep. You can use syg00's advice to acquire the equivalent, as a sort of catalog of what is where.

On future installations, be sure to assign LABELs to all filesystems, to make keeping track easier. You can add LABELs to filesystems at any time, and often use them in place of UUIDs to make identification easier on your eyes and brain.

Yet another option is to boot an installer image for one of the more common distros and stop at the disk partitioning stage. There you will have the choice to examine the disks and you can then find (and even erase) the odd partition by itself.