Q:

Crm2011: possible ways to hide delete ribbon button for [invoiceproduct] detail form

Just as the title, what are the possible ways to hide the delete ribbon button for [invoiceproduct] detail form.
When I log in as admin, I can see the delete button on the [invoiceproduct] detail form. However, when I log in as a special user who does not have the delete permission on [invoice], but has the append to permission on the [invoiceproduct] entity, I still can not see the Delete button. 
I do not understand how was the Delete button hidden for the special user.
Even In ribbon customization, it seems to there are several approaches.
BTW,
How can I restore the ribbon of [invoiceproduct] to its initial state? 
Thanks in advance

A:

Assuming no ribbon customizations are in place The button is hidden because the "special" user isn't authorized to do it by a security role.
Administrators can do anything, so they see everything.
If on the other hand the ribbon was customized Then some rule might also be in effect.

