[jQuery] Removing item from array based on property

Hello all,
I have a question about removing an item from an array.
I am looking to remove an item from the array based on the property.
Ie.
arr = [{a1: 1, a2: 2},{a1: 3, a2: 4}, {a1: 5, a2: 6}]
remove first item from array because a1 = 1.
I am not entirely sure how to do this. I tried messing around with
grep a bit, but that didn't turn out well.
Thanks