Swing it
Hit the rock face with a proper swing. Light taps do nothing, harder swings break more, and a second hand on the handle adds weight. Broken rock piles up as rubble, so walk close to collect it.
TipFists, axes and swords can break rock too, it just takes many more blows.
Better mauls
A stone maul chips away block by block. Copper and iron mauls from the Forge clear whole patches. Iron and gold take more blows than softer rock. Mauls wear out, see Tool wear.