To withdraw your funds from the mSOL/SOL liquidity pool, you have a couple of options.
You can visit old.marinade.finance to interact directly with the legacy interface, which still supports LP withdrawals.
Alternatively, you can go to Quarry the platform that manages the underlying liquidity mining programs — to manage your position, including unstaking your LP tokens and claiming any earned rewards.
Be sure to connect your wallet to the correct network and follow the on-screen instructions for a smooth withdrawal experience.