Rot Bot's Prefix is ) (Bracket Close)
Check the bot has the sufficient permissions in the channel you are trying to use it.
It requires at least Read and Send Messages.
Make sure to check channel permissions, and any other roles the bot has.
Are you typing the command correctly? View the command list to check the usage.
Unfortunately, currently, you can't change the prefix of the bot.
In the Future, we are looking to add this Feature
If you want to completely prevent the bot from being used in a channel, follow these steps:
Make sure the bot doesn't have the Administrator permissions in role settings, as this overrides any channel permissions.
Go the channel settings for the channel you don't want commands to be used.
Deny the Send Messages permission for Rot Bot.