I had Zorin 15 installed. I downloaded the new Zorin OS 16 and installed it alongside of Zorin OS 15. After trying the new Zorin OS 16, I like it! How do I uninstall the old Zorin OS 15 so that there is only Zorin OS 16?
You can do so with gparted.
In Gparted, select the partition that contains Zorin OS 15 and then click the ( - ) delete button on the lower left.
That partition will then show as Free Space. Select your Zorin OS 16 partition and select
move (or right click it and then select
move from the drop down menu). You can use the slider to expand Zorin OS 16 partition into the free space that was occupied by Zorin OS 15.
You must update grub once this has been done, since Zorin OS 15 was in grub.
Sudo apt update-grub
Open Nautilus (Files) and click "Other Locations. It should list the other partition in size and as /dev/sdaX - that will tell which is the Other One.