Discharge of charge is a rather broad term, but in the property industry this refers to when a mortgage is formally paid off. When this happens, the lender's Charge over the home is finally released. From this point on, neither the mortgage lender nor the bank can hold any claim to the property.
Unfortunately, some lenders may still require the property owner to pay an exit fee before they can discharge the mortgage. This fee, which is outlined in the owner's mortgage documents, may be higher if the mortgage is paid off earlier than the date agreed in the original contract.