If you want to blacklist an rcon command from being ran, you can use the /blacklist command.

The blacklist command has 3 options: add,del, and list. To add a command to blacklist (for example op): /blacklist action:add word:op ✅ Added op to Blacklist! /cmd op me This command is blacklisted by the Administrators!
To remove a command from blacklist, allowing everyone to run it again you can use the del option:
/blacklist action:del word:op ✅ Deleted op from blacklist! /cmd op me Command executed successfully!
You can get a list of blacklisted commands using the list option:
/blacklist action:list Blacklisted commands in current channel: op