Locking and Unlocking Channels

Use /mod lock [channel] to stop @everyone from sending messages in a channel. Omit channel to use the channel where you run the command. /mod unlock [channel] restores @everyone's Send Messages permission for the target channel.

You and Kakashi need Manage Channels in the target channel. Channel/category overwrites matter: having the permission at server level is not enough if the target channel denies it.

Locking edits the @everyone overwrite; it does not remove every role-specific allow. If another role explicitly grants Send Messages, members with that role may still be able to speak depending on Discord's permission resolution.