not an onion expert either but sounds like bolting onions to me bet there are seeds in those little onions as you call them if you mean at the top of the green some one will chime in that knows more but i would say leave them and let them mature if it is seeds.

They are the flower bulb; you can leave it but it will draw energy away from the bulb, which is what you really want. Pinch the flower bulb off at the tip. The onions are not mature until the leaves flop over and begin drying out.

NO take the tiny onions and plant them. they will grow big. I would not chop them off. If you had wanted to chop them off you should have done that long ago to prevent multiplication of the plants. Now the energy has gone into the main stalk and it is kind of late to remove the seedlings. I would let them go longer and as the plant seeds to die harvest the tiny bulbs and plant them.

Depends! If you truly have mini-onions growing on the tipes, you have one of the perennial "walking" onions. These bulblets can be used or planted. On the other hand if you talking a about a regular onion that has gone to seed, You can pinch the seedheads off if you want. It will slow the process a little bit, but I have never had any luck getting a good bulb once that seed stalk forms. It extends down into the bulb making them hollow.
Egyptian "walking" onion {{gwi:75377}}

Humblegyrl can you post a picture of your onion tops? Its easier to know what to recommend when we can see it.

If it looks like this, remove it:
{{gwi:75379}}

If it looks like small pearl onions, as in farmerdilla's picture, you can use them to start new plants.

I've had good luck getting a good onion with removing the flower bud BEFORE it opens; after it opens its 50-50 that the onion bulb will continue to increase in size.

I hope you dont mind me asking a question here about my onions. I started them from seed and babied them til they were about the size of a small marble, they had tops on them about 3 or 4 inches tall..(I had been clipping them back).

I planted them into the garden and the tops have disappeared. Not sure if anything is going on down below...any thoughts?