You can send them back to us or donate them to someone who can use them as feeder roaches (for reptiles and other pets). Also, there is an option to send you just male ones if you want to avoid the breeding process. 

Cockroaches who have gone through surgery and got electrodes inserted in them, you can leave in nature, somewhere far away from your home. But just carefully remove the Backpack from their backs and cut the electrodes.