If you delete documents from www.icloud.com they will also get deleted from iCloud Drive in the finder , and moved to trash folder .
If the documents are not in iCloud Drive either you have turned off desktops and documents see this article https://support.apple.com/en-gb/HT206985
When you turn off Desktop & Documents Folders, your files stay in iCloud Drive and a new Desktop and Documents folder is created on your Mac in the home folder. You can move files from iCloud Drive to your Mac as you need them, or select all of your files and drag them to the place you want to keep them.
- From your Mac, go to Apple menu
> System Preferences > iCloud. - Next to iCloud Drive, click Options.
- Deselect Desktop & Documents Folders.
- Click Done.
If you turn off iCloud Drive or sign out of iCloud, you have the option to keep a local copy of your files that are in iCloud Drive. Whether you decide to keep a local copy or not, a new Desktop and Documents folder is created in your home folder. If you choose to keep a local copy, your files in iCloud Drive are copied to a folder called iCloud Drive (Archive) in your home folder. Then you have the option to move any files that were in your iCloud Desktop and Documents, back to your new local Desktop and Documents.
If the iCloud storage is increased , you can reduce it see this article https://support.apple.com/en-in/HT204247
https://support.apple.com/en-in/guide/system-information/sysp4ee93ca4/mac
