How to uninstall an add-on that is hidden? [RESOLVED]

I have a policy product that depends in one deprecated package we want to remove (collective.z3cform.widgets).

My idea was simply to uninstall the package but it's hidden (from products and profiles) and so I get an error when I use the usual:

with api.env.adopt_roles(['Manager']):

I don't want to show it because I don't want anybody installing it by mistake after that.

is there any way I can tweak this feature programmatically? can I mark it as non-installable after uninstalling it?

My mistake, the package was not being declared in the configure.zcml file:

<include package="collective.z3cform.widgets" />