I am getting rid of Windows. I was looking at instructions found here: https://lifehacker.com/how-to-uninstall-windows-or-linux-after-dual-booting-508710422 and here: https://www.lifewire.com/remove-windows-linux-dual-boot-4177415
I did see this question Removing win8 ubuntu dual-boot and using just ubuntu here on Ask Ubuntu just now when I came to post. I can certainly try PartedMagic if it is better than gparted.
I still have my old live usb. I started to do this last night, but the machine did not recognize it. I came back this morning expecting to start with fixing the usb stick and/or port, but this time when I put it in, it came right up like nothing was ever wrong. That's probably not worth worrying about now, but I mention it just in case it means anything to you.
I opened the gparted gui, and deleted the Windows partition. However, when I went to re-size the Ubuntu partition, it was only giving me 26.9 GB of new space, which is way wrong, because the old Windows partition was over 600 GB. There is a way to create a new partition in, or out of, the old, now unallocated Windows space, and I can do that if that's my best solution, but I thought I would be able to just re-size my existing Ubuntu and that would be that.
Questions:
Is it possible to simply make my existing Ubuntu partition take up the now unallocated former Windows space or not?
There was also an option to 'Extend Partition', but that was greyed out. What would be the difference between 'extending' and 're-sizing'? If that is a good choice, how would I access the 'Extend' option?
UPDATE 1: I might have found the answer. If so I will come back and delete or point to my solution, but I have to reboot to test it...
UPDATE 2: These two answers, How to resize partitions? and Extending partitions which came up late in the 'similar questions' display, helped me.
It turns out that when the gparted dialog refers to 'space before' and 'space after', it is NOT, as I assumed, talking about chronologically, or temporally, but actual, physical space on the disk in front of or behind the partition you want to re-size.
In my case, that's a problem, as you can see from the picture I am posting. But there is sda7, which apparently could be extended into all the former Windows spaces. gparted says sda7 is mounted, but I can't see it when I look in files under 'other locations' where Windows used to be. I am sure there is a reason I created this separate Ubuntu partition, following whatever instructions I had at the time, but I don't remember why now. Any guesses?
So, now the goal is just to make as much space as possible available to Ubuntu, and be able to access it easily. Any thoughts on the best way to go about this greatly appreciated.