Solved Arg-2 is in {example::*}

[wCrazy_]

Sk version: 2.2
Server version: Spigot 1.8.8

        if arg-1 is "remove":
            if arg-2 is set:
                if arg-3 is not set:
                    if player has permission "duels.arena":
                        if arg-2 is in {duels.arenas::*}:
                            delete yaml "duels-arena-%arg-2%"
                            remove arg-2 from {duels.arenas::*}
                            send "%{duels.msg.arena.remove}%"
                            stop
                        else:
                            send "%{duels.msg.arena.not-created}%"
                            stop
                    else:
                        send "%{duels.msg.noperms}%"

 

[Minecoll_YT]

if {duels.arenas::*} contains world of arg-2:

 

[wCrazy_]

Worked! Thank you so much.

 

[Minecoll_YT]

Btw I recommend changing the whole variable to a list type of variable