How to "Force" Optimise Mac Storage to upload Desktop files and folders to iCloud

Dear Apple Community,

I have recently been looking into clearing up storage space on my MacBook Air (Early 2015, running Mojave 10.14.3)

It is still serving me well, but the "System" portion is taking over 75GB (I suspect it's filled with unnecessary files I should declutter). In my attempts to do so recently, I have mistakenly re-downloaded all of those files that had been stored online-only thanks to the "Optimise Mac Storage" feature.

I have activated such feature again now, but it's not clear to me when it will start deleting the local copies of these files and folders again and conserving them only in iCloud (in which I still have 25+GB worth of space).

I now have around 20GB worth of free space on my MacBook, but the moment it goes below 10GB, I can feel its performance decrease significantly.

My point is: I want to go back to having my folders and files "visible" on my MacBook, but for them not to be stored locally (such as when they appear with the little upload cloud logo next to them). When I right click on them, I only get the option to delete them by moving them to the trash, which would save me space but also make them disappear from my desktop: there is no "remove download" option. I don't want to wait for my Mac to do this for me over time because I would benefit from that space right now. Any suggestions?

Thank you kindly.