If "composition" refers to the act of creating something:
* Destruction: This directly opposes the act of creating.
* Deconstruction: This implies breaking something down into its parts, the opposite of building it up.
* Disassembly: This refers to taking something apart, the opposite of assembling it.
If "composition" refers to a piece of writing, art, or music:
* Improvisation: This is the opposite of a planned and structured work.
* Spontaneity: This emphasizes lack of pre-planning, as opposed to a carefully crafted composition.
* Chaos: This implies a lack of structure or organization, the opposite of a well-composed piece.
If "composition" refers to the makeup of something:
* Decomposition: This means breaking down into simpler parts, the opposite of combining elements.
* Disintegration: This refers to falling apart, the opposite of being put together.
* Separation: This implies the division of parts, the opposite of a unified composition.
To give you the most appropriate antonym, please provide more context about how "composition" is being used in your sentence.