How do I make a admin command that targets the player I name?

So I've been searching FOREVER online to find out how to do this and I can never find out how I've tried making my own custom admin commands but I don't know how to target a player by name like if I were to put :kill guest123 I have no idea how to target that player I only know simple :kill all :kill me :kill others -- Can anybody solve this for me please?

Hold on there cheif, have you made an admin command system yet? If so, you'd have to literally show us how that worked. Then we could actually help you. But from the info you already gave, make the script look through the playerlist and make a string.match from the name being chatted/commanded and the player in the list.