the Optimization check box actually would be responsible for deleting the files from your local disk, actually, after it claims or thinks that they are safe in the cloud, if, it thinks your local disk is sort of full.(this is actually the way you need to think about this one, since i have nowhere seen the actual rules and timing about lack of recent use that would cause files to be deleted from a local hard disk)
the check box that would actually be responsible for sending the files is the one that says you want to store your Desktop and Documents files in the cloud. but you have not checked that one, so not to worry.