How to upload directory while gaining local storage?

I synchronized a local directory with my NextCloud, however everything I upload on NextCloud is also needing space on my local computer.

Sorry to asking for help but I don’t find any solution until now :frowning:

What I would like to do is :
1 Upload the biggest directory on my cloud
2 Quite the synchonisation of the directories I put in
3 Delete the local directory (while keeping it safe on my cloud)
4 Access from local machine to the directory stored in order to open files

The problem is :
I didn’t find any useful tuto to make it this way
If I delete any file either on my cloud or on my local desktop it’s deleted from both.

Details
Nextcloud 17.0.2
Ubuntu
Local machine : MacOS Catalina 10.15.3

Thanks all from your help