When to decline other offers when you have decided on one?

When to decline other offers when you have decided on one?

I received an offer for an engineer role at a big tech corporate on June 7. While I was negotiating on this offer, I got scheduled for interviews with another group for a different engineer role at the same company. Everything went well, and the hiring manager wanted to make me an offer. I'm leaning towards the second role and will accept this offer once I get a written one. The problem is the HR person assigned to this role is slow. It took her 2 days to schedule a Teams meeting with me to just discuss the offer, but I don't know what we'll be talking about since I'll be given the exactly same package as the one I got previously (she knew about my first offer). This company has a non-competing policy if the same candidate get the offers from two groups, so I don't think I can negotiate further. The meeting with the HR person is scheduled at 4:30pm today, and this coming Monday is a holiday for them. It's likely I won't get my written offer until Tue or later. I told the hiring manager of the first role that I would let him know by the end of this week, so now I'm feeling bad for dragging it longer.