PART

The PART command is used to leave a channel (or multiple channels).

Channel Departure
Usage: PART <channel>{,<channel>} [<message>]
<channel> The name of the channel to leave.
<message> An optional message indicating the reason for leaving.

When a client issues a PART command, they are removed from the specified channel(s). If a part message is provided, it is sent to the channel as a part notice.

(See section 4.2.2 of RFC 1459, 3.2.2 of RFC 2812)