I think it's better to wait until fall when they can safely be dug up and relocated. Use a garden fork so you don't damage the bulbs. Having said that, I'm sure they could be moved anytime, but I believe you would have more success relocating then. The leaves turn yellow early on allium and soon disappear altogether which suits me fine. I don't have to look at them all summer long. It helps to plant them where the yellowing leaves will be covered by other plants or foliage.