How to hide uncategory category from the sidebar?

Hi,

I have uncategory category showing in my Sidebar here https://www.sraigiuauginimas.lt. As I understand it’s a default category, so I cannot delete it. In categories list it shows it has 12 posts under it (that’s a total of posts), but when you open it – there is nothing there. All posts are under relevant categories.

Is there a way to hide it from the sidebar? We use WP 2.9.2.

Thank you!