If the scab seems dried and loose then I would remove it, but if it's still pretty well attached I would give it some more time. It should fall off on its own but if it starts to interfere with skin regrowth then it probably should be removed. I had to do that in one spot where there was a lump from the skin being torn and the scab started to be lodged under the new skin.
My CVS was out of betadine at the time too, so I used povidone iodine 10% solution. I'm sure it stung a bit, but it really helped kill off germs and expedite healing. I felt bad the first few days because she didn't like it but I think that's because there was some icky stuff in the wound being killed off. I definitely would not apply alcohol; that would be much too strong. Since the skin looks a little green in that one spot, I think you might want to use something fairly strong right now or get the antibiotic powder to apply after you clean the wound. I also gave my girl some oral antibiotics for a week or two.
Wet cat food is supposed to be great for sick/traumatized birds, so if she's not eating much I would give her some. Protein is important for feather regrowth, so I gave my girl lots of mealworms (fresh) and other high protein treats. Cat food would probably be great for that as well.
Keep us posted!