I'm no gardener really but I just leave them in the pot and put them in the shed, having cut the flower stems off. The leaves die off but their goodness goes back into the bulb ( so I am told) and then I plant them in the ground. It's always worked for me.
Remove leaves and flowers and soil until you have only the bare bulbs. Dry the bulbs completely or they may rot. You don't need to plant them in the garden until late autumn. Keep them in a cool dry shed or garage in the meanwhile.
They won't flower again as indoor plants, but will flower outside if you plant the bulbs in the garden before next winter. They won't be as good either.