Unable to extend my C drive partition from unallocated space

I have found that when dealing with "awkward" systems it is best to perform each stage separately.
I would move the partitions to the left one at a time, (with reboots to check in between).

I have also found that the "Enhanced Data Protection" mode can prevent some operations from completing correctly, so you may wish to try with this option off, (ensure your Image/Backups are up to date to be safe)

First, did you make a backup of your Disk 0?
Always a good idea, just in case.
If you don't have a Image backup program, try the free Macrium Reflect

Unallocated space is what you get when you delete a partition, it has already been deleted so you can't delete it again as there is nothing there.

From your snips everything looks correct.
After selecting the 'OK' on your second snip, are you clicking the Apply button?
It's the big green check mark in the upper left corner.

If you have already tried this, what if any error messages are you getting?

Just to re-clarify :)

As Dave has said above the space is shown as unallocated so is in the state required, (there are only two partitions on the drive).

to extend either of the existing partitions you may need to first move one or both to the left and then extend the existing partition to the right, (into the unallocated space).

PW will allow you to extend to the left but the unallocated space must be adjacent to the partition to be extended