I mean you can answer your own question from those screenshots, you can see Windows folder is 19GB.
The issue you're having is due to memory resource files. First one, pagefile.sys is something like swap on Linux, when your RAM is close to full, it moves the least used data from your memory to that file, and loads it back on when you request it. What you can do with this is measure your RAM peak usage and set this to several more gigs for failsafety.
So if you have 16GB RAM but never use all 16GB, there is no point in having additional 16GB of swap space. In that case try setting your pagefile to 4 or 8GB just in case you load something big in there.
Second file hiberfil.sys is where Windows stores all memory content when you put your PC in hibernation. Sleep makes all data stay in memory, hibernation saves it on disk so you can power it off. If you want to delete that file and gain some more space just disable hibernation from control panel.