This question asks how PCs can break a stone wall. Aside from the usage of disintigrate to immediately destroy a wall, it seems that a wall can be destroyed by reducing it's HP to 0. Walls have a hardness which reduces the damage done to them.
What is the lowest level at which a player character can destroy a wall in 1 round? Magical and mundane means are both in scope, and any item which the character has access to. Limit items to the character's level or lower.