How to remove an element from a javascript array

I have an array as below

var array = [];

var item1 = 'k1';
var itemvalue1 = {'key1':'value1'};
array[item1] = itemvalue1;

var item2 = 'k2';
var itemvalue2 = {'key2':'value2'};
array[item2] = itemvalue2;

Two questions...

1. How to get the position(index) of the item2 in the array
2. How to remove the item item2 from the array

Any help is appreciated.

via Riyas