HBO Max - Unsupported Version

When I try to access HBO Max I get the message: 'Unsupported Version, Update you HBO Max app to get the latest features."  This was working one day and not the next.  I do have HBO (I can get HBO Max on my iphone).  I have Cox Contour and a smart TV.  I called Cox and was told I needed to contact HBO.  Needless to say they never called me back.  I don't know how to delete the app and reload it.  I was told on a second attempt to call Cox that there is no way to delete the app.  Help!!!