By changing the prefix, how does one form the antonym of ‘complicate?'
If you replace the prefix "com" with "ex" you have the word "explicate." Complicated can mean to make something complex, involved, intricate and difficult. In biology, complicate means to fold on itself or in entomology, to fold over longitudinally one or more times (like the wing of an insect).
Explicate means to explain, interpret, make plain or clear. It can also mean to formulate and develop a theory or an argument. This word is often used in poetic analysis. In explicating a poem, we uncover hidden meanings and metaphors, explain obscure references, and literally "unfold" the layers of meaning and symbols.