They didn't have many knives with them, but the incision to remove the trackers was even faster than Wolfe could cast [Wind Blades] and unlock the wristbands.
It also didn't need any magical input, so they could all do it themselves, and even the most squeamish were eager to get any trace of their time in captivity out of their bodies.
June cast a light spell so that everyone could see to work as the natural light faded, and Wolfe finished with the removal of the wristbands. It was an oversight not to have brought a box to store the wristbands in, but he could bury them easily enough, and they would likely stay lost unless they had a tracker in them as well.