Want the Approve/Deny buttons to disappear once ticket is approved.

You can use a Form Rule to control the Show / Hide on fields.  As for hiding the instructional text, you cannot use a form rule to show/ hide on a Rich Text element on a form.  So you would either need to put that message in a section, and then control the section by a form rule, or else make a Rich Text formula field to make a similar message, and then use that on the form instead of the Rich Text Element.