Solution to your problem. Get a spinning wire brush that attaches to your drill. I have used these for this exact application.
https://www.amazon.com/BLACK-DECKER-70-609-3-Inch-Coarse/dp/B000RGWY9W/ref=sr_1_3?dchild=1&keywords=drill+wire+brush&qid=1599771573&s=home-garden&sr=1-3
https://www.amazon.com/3M-Paint-Rust-Stripper-Brush/dp/B000BQT4UK/ref=sr_1_3?dchild=1&keywords=drill+wire+brush&qid=1599771609&s=home-garden&sr=1-3