Can massages release harmful toxins into the body?

In theory yes, but..: One could conceive of a way in which rubbing your muscles vigorously might cause muscle waste products to leak into your circulation--so does exercising. But you do not need to buy anything fancy to detox that. Your kidneys, if healthy, do an excellent job of cleaning your blood by themselves. All you need is water to ensure that you are well hydrated. Your body will do the rest.