Is a rusted hitch safe?
While a small amount of rust may not compromise the utility of your hitch, sometimes rust can hide signs of deeper structural damage to your hitch. It is better to err on the side of safety and explore a new hitch if you notice any significant signs of rust.
How do I get rust off my hitch receiver?
Removing a Rusty, Stuck Ball Mount & Hitch Ball
Try spraying the areas around the receiver opening with WD-40 and then use a rubber hammer to help knock the ball mount loose. Once it's free you can either pull it out or gently tap it out with the hammer.