Corns are a common disorder on the foot. They are a natural reaction to pressure as the skin thickens up to protect itself from that pressure. At some stage this process fails and becomes so thick that it's painful. There's a persistent myth that corns have roots which they keep growing back from once you try and take them off. This is just like the analogy of plants which re-grow from their roots if you chop the top of the plants off. That analogy has been applied to corns since they carry on growing back, however they don't have roots to grow back from.
Corns develop from pressure and a proficient podiatrist can readily eliminate a corn. The problem is that after the corn is taken away if the pressure that caused it is still there then, obviously, it is going to grow back. It develops back simply because the cause continues rather than because the podiatrist left a root there for the corn to develop back from. That pressure may be from a poor fitting shoe or from something like a claw toe or bunion leading to greater pressure on an area. When the corn is underneath the foot, then the cause is elevated pressure on the area where the corn is, probably due to the way you walk.
The myth persists since they do return, so its necessary to take away the cause when the corn is removed. There is absolutely no root to be taken out. This means that the pressure over the foot where the corn had been has to be reduced or removed. This can involve issues like using better fitting footwear or the use of padding to get pressure off the area where the corn is. Sometimes surgery can be needed to the bone beneath the corn to eliminate the pressure. If that cause is not taken away or reduced then the corn will return, so it's clear to understand where the myth regarding corn roots derives from.