'Prepare' is not the opposite of 'demolish'; 'build' or 'construct' are two words that are opposites of 'demolish'.
build
In born is to give life, to exist therefore to die, cease to exist is the antonym. To build is the opposite of demolish
The opposite of build (assemble) is to demolish or disassemble. The opposite of build (raise, increase) would be to decrease, lower, or reduce.
The noun form for the verb to demolish are demolisher and demolishment. Another noun form is demolition.
The opposite of construction is destruction.
hang a civilian who attempted to demolish the bridge
demolish = a demola
Demolish is a verb.
The man had to demolish the car in thirty seconds.
There is no opposite of the noun condition, but the opposite of the verb (meaning to prepare, adapt, or improve) could be slacken or worsen.
demolish=level (for a building)
it will cost exactly $10,000 to demolish a house