how can I clear my iPad if i do not know the apple id password?

WE have 2 iPad 2's that we use in our animal hospital. We had a practice manager set them up for texting and minor photo sharing. Unfortunately she is no longer here and I am trying to add an application. i cannot do anything without the password and we do not have an email address know that would have been the set up email. Can anyone help with this? We are willing to reset the unit but... even that requires a password! Dr. Burke