From Ground: If the aromatic aster is currently growing in the ground, the first step is to water the plant to moisten the soil, making it easier to remove. Once the soil is wet, dig a wide trench around the plant using your spade or shovel. Be sure to dig deep enough so you don't disrupt the root ball. Once the trench is dug, slowly work your spade under the root ball, lifting the plant from its original location. Take care not to damage the root system.
From Pot: Similarly, if the aromatic aster is in a pot, water the plant first to moisten the soil. Invert the pot while supporting the plant at the base of its stem with your other hand. Gently encourage the plant to slide out, wiggling it a bit if necessary. If the plant doesn't remove easily, you might need to tap the rim of the pot against the edge of a solid surface.
From Seedling Tray: To remove the aromatic aster from a seedling tray, make sure the soil is moist first. Gently hold the aromatic aster at the base of its stem and leverage with a small tool such as a butter knife to loosen it. Lift the plant out, while making sure not to harm the root system.