The Hammer power-up clears everything from a single cell. That means most blockers and blocks, regardless of how many layers they have.
The exceptions are:
- Locks
- Hives (if there's honey around it)
- Candles (hammer can light them up, but not remove them)
- Boxing bags (hammer hits them once but doesn't remove them)
- Bowling balls and pins
To use the hammer, simply tap the hammer button and then the cell you wish to clear.