Prune dead leaves any time of year. However, a good time to remove dead leaves from a corn plant is before you move it outdoors for the summer or indoors for the winter, if applicable.
Sterilize a pair of hand clippers with rubbing alcohol to prevent the spread of disease from one plant to another. You can also clean the pair with a cleaning solution made from 1 part bleach and 9 parts water. Moisten a rag with the rubbing alcohol or bleach solution; carefully rub both sides of the blades.
Cut the dead leaves off at the bottom of the stems where they meet the trunk. Some leaves may easily pull away from the trunk, but if not use the garden clippers. Discard the cut leaves in the trash or compost pile.