Question for the master gardeners.

Planted a bunch of Onion sets this spring purple, yellow and white. Have been eating them all summer in salads but still have a bunch that I have not used.

The tops seem mostly broken over and yellow or brown and seem mostly done in growing larger. 

Onions seem to be mostly 2-4" in diameter at this point in time.

What is the best way to preserve these and keep them for later use going in to fall/winter. How long can they be kept ?

Am I better off leaving in the ground until colder temperatures ? Pulling them now and leaving whole and hanging to dry ? Pulling now and removing tops but do nothing to bulbs and hang in mesh potato bag in a cool dry place ?

Any need to refrigerate until cut for use ?

Never really tried keeping large volume of onions for later use.

Thanks in advance.