Use RC and say:
/clearnpcs LEVEL
edit: staffblock NPC
NPC Code:
if (playerchats&&strequals(#a,Gman)){
if (strequals(#c,destroy)) destroy;
}
Like that, you won't need to "clearnpcs", but simply say "destroy" on player.
EDIT 2: I should read your question.
NPC Code:
if (created){
setshape 1,32,32;
}
^ That should be placed serverside. The triggeraction doesn't detect the trigger because the shape doesn't have a width/length. To fix that, you must put it. Common error.