Not sure OEMY
ever worked on his wipers but has many other repairs shown in his web site.
Why do you need to remove, if its to repaint I used news paper over windshield and spray painted them.
Their maybe a nut at base of arm that clamps arm to the pin its attached to, never really needed to remove and I can not now remember my last coach.
A Newmar search may tell us. --- RESULT
-- ---- and this one
maybe close to info you need.