Hey, Im using Orange NoDecay plugin, and when I use the command I receive this message

https://prnt.sc/uifoh7

I guess you did not give yourself the right permissions to use the command. As stated on the plugin page:

nodecay.use -- Required for NoDecay to work for a user, if the usePermission flag is set to true.
nodecay.admin -- Required to use the /nodecay commands below​

If that's not the case, I think you are using just the command /nodecay, but i think that doesn't do anything since you have to add "log", "info" or "enable" to it:

nodecay log -- Toggle logging of debug info to oxide log and rcon
nodecay info -- Display current configuration (must still set manually and reload)
nodecay enable -- Toggle enable/disable of the plugin. This can only be switched off/on via chat and the plugin will always default to enabled on reload.