Have m. Catarrhalis bacteria sinus infection. Have been neti pot and fever gone and pressure, congestion better. Do I still need the the azithro?

Yes. If you don't, there's a good chance the infection will just come back within a few days.
How many days. Of Azithromycin have you had already? Usually a 5 day course is more than adequate to eliminate the bacteria. I would complete the course your doctor recommended to be sure you completely eradicate it, but in general a z-pack duration is enough (3-5 days).