Icloud Drive Storage Problem
My Icloud drive seems that it is 4.95GB full, but there is not any files inside, even in deleted items. So how can I make it 0 as it should be?
Your files from your device are only one type of content which goes towards your use of iCloud space.
For an explanation of the types of data which can take up space on iCloud see What you can do with iCloud storage.
Check your iCloud storage on any device will show you how to see what is taking up space on your iCloud.