Have by your side an install stick for LM 19 Cinnamon. If things go pear-shaped, we can use its Timeshift to restore from the snapshot you have taken, and which last I saw would be in /dev/sda3 on the HDD.
In Linux Mint on the SSD, launch GParted and navigate to the page for /dev/sdb. (We could also perform this operation from Ubuntu, but we want to be able to update our Grub Menu, and that is done through Mint which is currently in charge).
It should be the case that none of the partitions on the SSD has that lock padlock or key beside them, that is, they should be unmounted. If any are not, right-click the partition entry and choose "unmount", or in the case of Swap "swapoff" - these ops will action immediately.
Starting with /dev/sdb3 which should be Swap, right-click and choose delete, but do not yet choose the green tick/checkmark to apply.
Continue down the list, to and including /dev/sdb6 which was also Swap, right-click and delete each time.
You will notice a pane at the bottom of GParted's window which is accumulating a list of tasks pending, grow.
When you get to the point where all occupied partitions other than those of Linux Mint have been set up to delete, then, Apply the changes, you may get a non-fatal warning, proceed.
After a short time, all operations are completed and you are left with /dev/sdb1 and /dev/sdb2. Your unallocated space has grown into one contiguous lot.
Exit GParted but do not reboot.
STEP THE NEXT
Open a Terminal Ctrl-Alt-t.
On the subject of Control keys, an upward-pointing caret ^ can be used for Control, so ^C is the same as Ctrl-C - this protocol will be used in Nano, command line text editor.
Type and enter the following
Enter your password and proceed.
The file in front of you will look a little similar to ones where I have asked for "cat /etc/fstab", but rather than just having its content
typed to the screen, here we are going to
edit its content.
Navigation is by your arrow keys, left, right, up, down - although we will employ a slightly more user-friendly approach with larger files coming up.
Check at the bottom of the file for a line or lines referring to Swap or a swapfile. I am thinking it would reference /dev/sdb3.
If there is a line prefaced with a hash # that is a comment, and is simply explanatory. If there is a line without a hash, that is a command or a reference or directions for Linux to find things.
So if there is a line of that sort referencing Swap, go to the start of the line and insert a # or a # and space (programmers like the space).
Now, following the instructions at the bottom of the Nano "shell", we are going to ^X to start the exit and save.
You will be prompted to save or discard changes, choose Shift-Y for Yes. The name of the file to save will be displayed, press enter and you are returned to the Terminal shell.
STEP THE LAST
For quite a number of Distros in different Families, that is sufficient to effect the changes. We won't take any chances.
In Terminal
Enter your password and proceed. Once Grub is updated ...
Reboot.
Let us know how you go, and then we will proceed further, or fix any glitches.
Cheers
Wizard