From Ground: If devil's trumpet is currently in ground, water it lightly so the soil around the roots will hold together better. Use a trowel to dig a wide circle around the plant, keeping a fair distance from the stem to avoid damaging the roots. Slowly dig under the plant, lifting the root ball out of the ground gently. Aim to keep as much of the soil around the roots intact to minimize transplant shock.
From Pot: If devil's trumpet is in a pot, water it moderately to help the soil stick together. Turn the pot sideways and, while holding the plant at the base, gently tap the rim of the pot on a firm surface to loosen the root ball. Tilt the pot and ease the plant out, supporting the root ball. If it's stuck, try pushing from the drainage hole at the bottom.
From Seedling Tray: If devil's trumpet is in a seedling tray, it's best to transplant when the plant is about 3 inches tall. Water the tray to moisten the soil. Use a spoon or small tool to ease out the root ball with the surrounding soil, taking care not to damage the delicate roots. Always hold the plant by its leaves, not by the stem.