How do you destroy walls behind your house?

How can I destroy the blocks I placed to create the 'back wall' behind my house?

Walls "behind" the scenery can be removed using a hammer.

Here are some of the early hammers, with instructions on how to craft them:

• Wooden Hammer: 8x Wood 2 Damage, Very slow speed, 25% Hammer Power
• Copper Hammer: 10x Copper bar, 3x wood 4 Damage, Very Slow speed, 35% Hammer Power
• Iron Hammer: 10x Iron Bar 3x Wood 7 Damage, Slow speed, 45% more Hammer Power
• Gold Hammer: 10x Gold Bar 3x Wood 9 Damage, Slow speed, 55% Hammer Power
• Meteorite Hamaxe: 35x Meteorite Bar 20 Damage, Slow speed, 60% Hammer Power, 20% Axe Power

For a full list of hammers and hamaxes (hammers and axes in one tool), see the wiki.