1. Godan verb with 'su' ending, Transitive verb

   to destroy; to break (by striking); to smash; to knock down

   彼らは箱をこなごなに打ち壊した。

2. to ruin (a plan, atmosphere, etc.); to spoil; to wreck

Also written 打ち壊す【ぶちこわす】buchikowasu、打ち毀す【ぶちこわす】buchikowasu