I want to delete the Niagara system.

I want to delete the Niagara system.

I want to delete an unused Niagara system.
But often it’s impossible to delete
When you delete, a very long message appears and the deletion fails.
In short, it means that the Niagara system that you want to delete is in use.
But this Niagara system was not used in my project.
It’s just in the content browser.
If you know how to fix it, please let me know. help me