How to deter cockatoos?

Hang a feeder for them somewhere outside of the apartment building. Perhaps on the side of the building where the seeds won’t bother any of your neighbors. Maybe hang it in the courtyard of your building if you have one. They should find it and stay there if you keep it filled.
Good luck.

I would purchase bird spikes like these for your window sills. (Please shop around- I did not price check and that might not be the best deal.) They are humane and will keep the birds away.

I would also put a feeder in an acceptable location away from the building just because it is a cool thing to do.

I shoot them with a water pistol. The don’t like it and stay away. I haven’t actuially used it on a cockatoo but it sure shuts up a noisy parrot.

How ironic, I was looking through my ancient profile messages and came across a thank you reply for my answer to this question from the OP, when I followed the link I found my answer was not here and I assume it was moderated : ^)