Do you need to vent an electric tankless water heater?

No.

Unlike gas tankless water heaters and gas traditional tank style water heaters, electric tankless water heaters do not require any venting. This is often one of the deciding factors when choosing whether you should purchase a gas or electric tankless water heater. Since no venting is required for electric tankless, their installation cost is often cheaper and they don't suffer the same heat loss that gas tankless water heaters do through the vented air. This lack of venting is one of the main reasons electric tankless water heaters operate at a much higher efficiency (usually 99%+ efficiency) than gas tankless water heaters (usually 80 - 85% efficient).