The last chunk is the one everybody pictures, and it's the one with the most paperwork. The mortgage balance is down to $38,000, the line of credit has $50,000 of room, and it's time to end it.
Start with a payoff statement, not the balance on your monthly statement. Mortgage interest is paid in arrears, so the balance you see doesn't include the interest that's accrued since your last payment, and the payoff quote adds it through a specific date, along with a per-diem figure for each day past that. There may be a recording fee for the lien release and sometimes a fee for the statement itself. The quote is good for a window, usually a couple of weeks. Send the money inside it, by wire or cashier's check the way the servicer specifies, and send a little over rather than a little under. They refund the difference. A short payment leaves the loan open and accruing.
Size the chunk against the never-max rule before you send it. Thirty-eight thousand on a $50,000 line of credit is 76% utilization, which is above where I'd want anyone to sit for long. Two chunks a few months apart is the safer version, and the mortgage doesn't care whether it dies in one move or two. Only the last one needs the payoff statement.
After the payoff, three things happen without you. The servicer refunds whatever's left in escrow, which federal rules require within a few weeks. The lender records a release of the lien with the county, in Oregon a deed of reconveyance, and state law puts a deadline on them to do it. And the servicer sends a paid-in-full letter. Keep the letter, and check the county records a month or two later to confirm the reconveyance is on file, because a missing release is a much bigger problem the week you sell.
Then two bills start coming to you. Property tax arrives from the county in October, and the homeowner's policy renews with the insurer instead of through escrow. Both belong on the line of credit like every other big irregular bill. Call the insurer and have the mortgagee clause removed from the policy, or a claim check can still get mailed with the old lender's name on it.
The line of credit is now the only lien on the house. And the last chunk gets paid back through the same sweep as the first one, on the same schedule. Once it's paid off, the plan changes targets, and what it does next is in what Dynamic Banking does after the mortgage is gone. The first move is the phone call for the payoff statement, with a date about ten days out.