how to exclude categories

You are not providing nearly enough information.

“Exclude categories” is only available for tree types that have categories. You are probably looking at a widget where “category” would have no meaning.

Let me give the following example of tree types category in my sidebar:

Subjects (Main Category)
– Science (sub-category of Subjects)
– Geography
– History
– Mathematics
– Literature
– Languages

In the above example, for example I would like to exclude “History” in my sidebar as I have created a custom menu and “History” is in my custom menu.

Thank you & regards,
Koh, Kah Huat

0. locate the ID of the “History” category
1. open the WP-dTree Categories widget settings
2. add the ID to the field named “Exclude:”
3. click “Save”