Wash them out with a nozzle on the end of a garden hose. There should be a drain/weep hole in the bottom of them but it may be clogged up. If that does not work then you can probably stuff a piece of a pool noodle in there to dislodge some water and just leave it in there over the winter to absorb any freezing pressure from water remaining.
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Welcome to TFP! For a wealth of pool care information please check out our free Pool School. If you are in need of specific help then we encourage you to Register and ask us here in the forum!