let removeMaximum = (array) => {
    // find maximum in array and it's index
    let maximum = 0;
    for (let i = 0; i < array.length; i++) {
        if (maximum < array[i]) {
            maximum = array[i];
        }
    }

    // remove 1 element of value maximum
    array = array.filter(function(value, index, arr){
        return value !== maximum;
    });
    return array;
}

let a = [1, 2, 3, 10, 5, 100, 8, 15];
let arrayWithoutMaximum = removeMaximum(a);
console.log(arrayWithoutMaximum);