There is actually alot of content on this site about the subject of pyramiding. You may want to do some searching of old threads to gain some more in depth information but basically keep your tortoise well hydrated, not only drinking water but the substrate and ambient air humidity also. Low protein diet, plenty of room for activity.
If you have a baby or very young tortoise new pyramiding is absolutely avoidable and any previous pyramiding can be controlled (although not reversed) if the tortoise is cared for correctly. If it is an older tortoise that is pyramided there is no reversing it at that point. In that case a good quality, varied diet and other correct care measures will help the tortoise live as long and as healthy as possible.