const re = [1,2,3,4,5]
const value = 7

for(var x in re){
  for(var y in re){

    if(re[x]+re[y] === value && re[x]!== re[y]){

      console.log("found"+x)

      re[x] = NaN
      re[y] = NaN
    }


  }

}

console.log(re)