VK12 disable buttom "change validity"

Hi Gurus

In transaction VK12, is it possible to disable the buttom "Change validity"?

We created an exit to permit only some users, according to their hierarchy in the company (managers), to be able to change the fields for valid dates, but we can't do the same for the buttons "Change validity" that has the same functionality.

Regards,

Adilson Ferreira