My ICloud is almost empty but my device is full storage. How make space in my device?

I think the reference below may be more useful. The one in a previous post refers to cellular data use which is not the same as storage.

See how much storage you've used on your iPhone, iPad, and iPod touch - Apple Support - http://support.apple.com/HT201656

Also read the tips at the end of the document.

Check the data usage on your iPhone and iPad - Apple Support