If "portray" means "to depict" or "to represent":
* Misrepresent: To give a false or misleading account of.
* Distort: To twist or change something out of its true shape or meaning.
* Conceal: To hide or keep secret.
* Suppress: To prevent something from being known or expressed.
If "portray" means "to act" or "to play a role":
* Ignore: To refuse to pay attention to.
* Avoid: To keep away from.
* Neglect: To fail to give proper attention or care to.
If "portray" means "to describe" or "to characterize":
* Mischaracterize: To describe someone or something inaccurately.
* Understate: To present something as less important or serious than it really is.
Ultimately, the best antonym will depend on the specific context in which you're using the word "portray."