How do I delete a referenced file in a drawing?

Hello

I made a copy of a plan that referred to both a part and an assembly. I've deleted all the views that used assembly, but I'm keeping a reference in the PDM task pane

Volet des taches

I have searched in vain for a way to remove this link which no longer has any reason to exist.
When I open the " References " window when I open the plan, I could modify the referenced file, but no way to delete it...

Do you have any ideas?

Thank you in advance.