Draining water from pitless adapter to tank

My supply line from my deep well pitless adapter gradually slopes up to the above ground slab I have my pressure/holding tank on. How do I drain the water in that supply line so it won't freeze this winter. I'll be shutting the power off to the submersible pump for the winter. Is there a valve down in the casing or well head I"ll need to open/close?
Thanks,
jim

That's a question you will have to ask the installer of the system.

bob...