[SOLVED] Contact to Ressource to contact

Hi,
I have a contact (client) who can sometimes have activities in projects. I have tried to change is status as a ressource (external member team) but finally, it's not a good idea.
I then want to remove the "is a ressource" flag but when I uncheck in"contacts" page the "is a ressource", I have this message :

"Contrôles invalides.
Impossible de supprimer cet élément car il a des éléments dépendants
 - Assignation (3)

I have checked (but for sure, I missed something), he is not assigned anymore to activities.
How can I see where are the 3 assignations ? The "planning per ressource" gives nothing.
Many thanks !

Thanks, for your answer, but I still have issues :
- I cannot ask the ressource to connect because he is not a user, only a contact/ressource
- when I am connected with an admin account, the "Ressource planning" do not display any information on my ressource.
For me the ressource is not assigned anymore

Found !!
Related to Leaves and Administrative projects.
Item solved.