If I place an on-line order today, how long do I have to cancel this order if I change my mind?

I'm not sure. I ordered two air conditioners and picked the one I wanted when they came in.

1hr if same day pick up, or if delivery to store or home, before the order ships from the merchant.

I would think in a few hours after placing the order. The info on that would most likely be under information about Lowe's

30 days maybe