That doesn't sound like catawissa to me, at least not mine. There would be no need to take them out in fall.

I like to control mine so they are dug and replanted in rows. I collect the topsets carefully so they don't come up everwhere. I dig the bulbs a while after collecting the topsets. When the tops start to look old. Cure like onions or garlic and the bulbs can be used in stews, Etc. I like Heritage Sweet White even better. Below applies to either.

Our multiplier onion sets should be planted 1 inch
deep 4 to 6 inches apart. If you wish to increase the
white section of the plant for harvesting as table
scallions, the soil should be mounded around them as
they grow to a depth of about 3 or 4 inches.
In mid summer, the leaves will begin to die back from
the tips and start to fall over with top sets on the
stalks. At this time you should stop watering. Within
a few weeks, the bulb lets or sets will be ready for
harvesting. Dig them after the leaves have turned
yellow and brown and remove the top sets and replant.
Do not cut the stems at this time. Let them cure in a
warm dry spot until totally dry and the outer skin of
the bulb has turned to a papery feeling. At this time,
the stems can be removed to within one inch of the
bulb and the onions can now be stored in a cool dry
place at 34 F or grater for eating or planting.
(from original planting directions)

Thank you both for your replies. The man I got them from said he dug his and dried them so I thought maybe I should too. Mine don't spread very far from the 4X4 bed they're in. Do I need to pull off the tops and replant them in the ground or just let them plant themselves? I may go ahead and harvest some of them for drying and replant the top sets.

Nancy

Nancy,
If you let them plant themselves, they will grow in bunches. I prefer to plant my topsets and bottom bulbs in rows so I have some control over them. I do not have a permanent bed. If you leave the bottom bulbs in place, you will soon have a dense clump which I find hard to deal with. One single bottom bulb will divide into 3 to 5 new bottom bulbs. a single top set gives a nice straight green onion/scallion. Why not try it both ways and see which you like best?