I fixed ur skript buddy it has some errors and missing stuff here
command /undisrank <player>:
permission: Mini.RankDis
permission message: "&cYou are not authorized for this command!"
trigger:
if arg-1 is set:
make console execute command "pex user %arg-1% prefix "
send "&8You've reset &7%arg-1%&7's &8rank!"
if else:
send "[If you wanna make it to where it undisrank's you, feel free to add it. Or just send an error message.]"