As Simon says you can’t move any of your ships in that sea zone on NCM. There is a provision that allows you to move them to flee the sea zone on the Combat Movement phase without taking them into combat. The real purpose of the move though is to prevent any transports in the sea zone from loading ground units in that sea zone. You can still move to another sea zone on Combat Move and load ground units as long as it is a friendly sea zone. If you haven’t seen the video it explains everything;
https://www.youtube.com/watch?v=Pkj_9K3lfQk&t=166s