Paid is the four-letter word that indicates the party has reported satisfaction of the debt. It could be paid in full, or paid for less, but either way, the current status becomes paid.
Once paid, meaning the debt is satisfied, the party is also required to report a $0 balance.
On the flip side, reporting of a $0 balance does not indicate paid. It indicates that they no longer have a debt due them. If they sell the debt, they must report a $0 balance. The debt is still out there, and someone else can report it. If an OC does a charge-off and then sells the debt to a debt collector, the CO remains the last status, and they update the balance to $0. It can then re-appear in your CR should the new owner choose to report their collection on the debt.
A charge-off is a serious derog. Yes, it is worth the effort to attempt its deletion. If the OC no longer owns the debt, you cannot offer PFD, and must resort to requests for GW deletion. Having held your debt to be uncollectible, and if sold, having taken a loss of at least a portion of the debt, it is a bit tough to invoke their good-will. All you can do is give it a go.