jupyter labextension disable --level=user nbgrader/create_assignment doesn't work

[Mad31]

hi,
i use nbgradrer with jupyterlab 3.
I have student's accounts and i want to disable create_assignment for them.

I log in the hub with a student account, run in a terminal : jupyter labextension disable --level=user nbgrader/create_assignment
shutdown th hub and restart it...
create_assignment still here in the right bar !!

Can u help me ?

thank for youy fantastic job !