If i hit someones car and they say they don't want the insurance info can they demand it at a later time?

Yes, the other party can request your insurance information later, even if they initially say they don't want it. It's important to exchange insurance details at the time of the accident, as it helps protect both parties in case claims arise later. If they later decide to pursue a claim for damages or injuries, having the insurance information will be necessary. It's always best to document the incident and exchange relevant information regardless of initial statements.