To unlock this achievement you must demolish every building on every main mission (big circle missions on the world map, 20 in total). This should be done after first finishing all main missions as you can then do a clean up on each map without a time limit.
You can check progress on each mission by pressing A on each mission on the world map. When every pre-mission screen shows 100% for buildings destroyed the achievement will unlock.
Some buildings can be tricky to find but with some exploration you should be able to find all of them. If any give you trouble (maybe 5 at the most) find a YouTube video or online solution for that mission.
Note: big balls, lights and ships are classed as buildings so look out for them.
I hope this helps. If I can explain more clearly or help further leave a comment or message me. Cheers