Sport mirrors how do you pull them apart for painting?

They can be taken apart but really are not made to be taken apart. On the remote adjuster there are crimps where the cable is help in. Carefully pry those open just enough to slide the cable out. Your success will largely depend on the condition of the mirrors. If there is a lot of corrosion it will be hard to not break something in the process.
Safest bet is to just mask off the mirror and rotate the mirror to gain access to the inside for painting.