iCloud delete due to doubling space needed on computer

as I had to read somewhere else in this site, the iCloud sync means that the database data is copied to another area of my storage and then uploaded to iCloud, resulting in doubling the space needed for the same data on my storage. This explains why I am running out of space. Therefore I need to get rid of iCloud sync. Can someone please guide me to an explanation how to do this in a way / or explain it here, that I keep my databases but the doubled data on my drive is deleted?
Thanks for your help!

Your databases aren’t copied. It’s sync data synced locally then iCloud does its own uploading to Apple servers.

If you want to not use iCloud, right-click the iCloud sync location and choose Clean Location. This will remove the sync data and iCloud should eventually clean up the data on Apple’s servers as well.