Grinder with a cup wheel, vacuum, and PPE.

Thank you! Anything else special to keep in mind while doing it? Is there a chance of leaving little circles that will still be visible after painting?

Follow the cup wheel with a diamond pad protocol to remove any swirls. You'll have a nice exposed aggregate finish; no way I'd ruin that with paint. I'd put some densifier on it and call it good.

^^Absolutely. I would not ever paint exterior concrete. The paint will chip sooner than later.