I've never heard of Streptocarpus being 'stored'. I just leave mine alone, and treat them like any other house plant.
I don't think there's any need to do anything with the leaves, unless they are dying off or something, in which case you could remove them.

You can take them off now, as the leaves that have flowered this year will not flower again. Its the new leaves that will flower next year. Don't let them dry out through winter, just a little water, enough to keep them alive.

I didn't used to take the leaves of my Streptocarpus either. The plant was just looked after just the same as in summer but with less watering. I don't recall them having a flowering season either, just kept on going.

When I had a number of Streps I sometimes trimmed the larger leaves back with a pair of scissors to get them a better fit on the window ledge. They never seemed to mind this being done.