Can I disable the #required form attribute temporarily? I have functionality set up where an admin can create a user with a content profile. The content profile has a required field but I want the user himself to fill it out. How can I disable the required-ness of that field when the admin is creating the user so he can submit the form. I tried setting #required to 0 or unsetting it, but that does nothing.

function mymodule_form_contenttype_node_form_alter(&amp;$form, &amp;$form_state) {
        $form['field_reviewer_instruments']['#access'] = FALSE;
        $form['field_reviewer_instruments']['#required'] = FALSE;
}
This is most likely because of the ordering. THe module which is altering the form and setting the required element is being run after yours.

In the system table set your module weight to be higher than the module which is affecting the form.