Q.My Calla Lily Has A Leaf And One Flower Stem That Is Turning Yellow. Should I Trim It Off. Is That Normal Or Have I Over Watered
the plant. Should it be watered from the bottom or top. It is in a pot.

Certified GKH Gardening Expert
This is, likely, an indication that it needs feeding! These plants tend to like soil on the moist side, as they grow along riverbanks in the wild. Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily/container-grown-calla-lilies.htm
https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily/calla-lily-watering.htm
https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily