Icloud storage

iCloud is not designed to do that. It is a syncing service. If you want to potentially reduce the space used on your hard drive, see the following from Add your Desktop and Documents files to iCloud Drive - Apple Support

Store your files in iCloud and save space on your device

The files that you keep in iCloud Drive use your iCloud storage. And as long as you have enough space in iCloud and on your device, you can store as many files as you like. 

If you need more space on your device, iCloud Drive can help. On your Mac, choose Apple menu  > System Preferences. Click Apple ID, then click iCloud. On macOS Mojave or earlier, choose Apple menu  > System Preferences, then click iCloud. Turn on Optimize Mac Storage. Then your Mac keeps all of your recent files on your computer, but keeps your older ones only in iCloud, ready for you to download when you need them again. If you want to free up more space on your Mac, follow these steps. On your iPhone, iPad, or iPod touch, you can search and browse files from all of your devices and download them only as you need them.

You can also free up space on your device and in iCloud Drive when you delete files. Then go to your Recently Deleted folder in the Files app or on iCloud.com and delete the files there. Before you delete anything, make sure that you back up the files that you still want. When you use iCloud Drive and delete a file on one device, it deletes on your other devices too. iCloud removes the files from every device that you're signed in to with the same Apple ID.

If you delete files from Mac https://support.apple.com/en-in/guide/system-information/syspf5a64aa6/mac

The same files will be deleted from iCloud.com as iCloud Drive is turned as on https://support.apple.com/en-in/guide/mac-help/mchle5a61431/10.14/mac/10.14

https://support.apple.com/en-in/guide/icloud/mmd0b4a7f5e8/icloud

Perhaps there is other way not to delete files from Mac , rather drag and drop those files from Mac > to some other location , the files in icloud.com will be intact and not deleted https://support.apple.com/en-gb/guide/mac-help/mchl1a02d711/10.14/mac/10.14

• On your Mac, drag items from iCloud drive to another folder in the Finder sidebar or on the desktop, such as Downloads, Movies, Music and Pictures. 
• The items are copied to your Mac and removed from iCloud Drive on all your devices set up for iCloud. If you change your mind, you can drag items back to iCloud Drive.