If you are in a climate that freezes, either keep the flagpole extended in the full upright position OR take it in for the winter. Do not keep the flagpole sitting down in the installation sleeve in the lowered position. Make sure to check your installation sleeve for proper drainage before frost hits. Sometime in the fall, pull the flagpole up out of the sleeve and make sure the sleeve is dry.
If you wish to lower the flagpole in the winter, lower it all the way down, pull it up out of the sleeve, and store inside for the winter. This will prevent any ice damage that may occur if the sleeve is not draining properly.