Per the instructions at the link below:

1.Dig the calla lily bulbs from the ground before the first frost.(or in your case, remove from the pot)
2.Clean excess soil from the bulbs and lay them in the direct sun for a few days.
3.Place the bulbs in a plastic bin or bucket among layers of peat moss.
4.Store the bulbs in a dry location that will maintain a temperature between 50 and 60 degrees throughout the winter.
5.Replant the bulbs when night temperatures reach 55 degrees or greater in the spring and the danger of frost has passed.

The link also describes how to overwinter it leaving it in the pot.

Sue

Here is a link that might be useful: How to Winterize Calla Lillies

I leave mine in the pots bring them in for the winter.
The leaves are usually dead by the time I bring in my pots. I cut off the dead leaves and store them in laundry room temps are 60-70.

They start putting up leaves about March I start giving them a sip of water not enough to wet the soil but enough so it is not bone dry. About 1/2 cup.

I have been doing that for 6 years with good success.

Interesting choices, :)

Thank you both. Now I have some thinking to do...