Of course you can’t! But that does not stop people promoting it. The whole detox movement has been getting a lot of mileage and is based on removing toxins from the body. Pretty much every bit of science has totally debunked it, but that does not stop people promoting it. The idea of a foot detox is to remove toxins from the body via the foot. Various pads and electrical currents are used to achieve this. During the process the pads that are used change color, so this is used as evidence that toxins have been removed. Again, all the scientific evidence is that this is wrong and does not happen, but that does not stop people promoting it.
The foot detox is a scam. Do not fall for it. Spend your money on something more productive.