Question: what episode does the mandalorian take his helmet off?
Answer: In episode 4, “Sanctuary,” the Mandalorian explained to Omera (the widow from the village he helped save) that Mandalorians can take off their helmets! Just, you know, not in front of other people. That's how the Mandalorian eats, as evidenced right after this conversation, where he takes off his helmet to eat alone.