Changing or Removing Fields from Contact Page

Hi,

How/where do you go to change or remove what fields are present on the Conact form page. The default one has a place for users to insert a phone number and this is an irrelevent field for my type of site.
It is even a bit difficult to use custom css because each field is wrapped in a div called “form-group”.

Is this something where I would have to edit on of the template files or is there an option within the GUI?
I don’t mind editing the php file I just need you to tell which one if that is the case.