Opps, sorry for the delay. I was taking an internet break for a week on vaca.
Not sure I understand the question. I do not know what “disable .insync-trash entirely” or “manually clear it” means.
I would envision this working similar to the way dropbox does it. If you uncheck the folder, then the folder disappears from your computer, you can continue to access the file(s) in the cloud but the file(s) are removed from your computer and thus the space is cleared from your computer. This is what the warning message says happens when you do this:
“You have unselected some files and folders. They will be removed from this machine, but will remain on your Google Drive.”
But what happened with me is that I can no longer see the file(s) on the machine but the space on my computer is not freed up. The file(s) are also not in my trash so it is not a matter of my simply clearing my trash to free up the space.
I am doing something wrong? As I really can’t imagine any other way this feature would work.