Porterfield was scheduled to compete in next month's Miss USA pageant in Las Vegas but gave up her title Friday, the Milwaukee Journal Sentinel said Monday.
She has pleaded not guilty to misappropriating identity information to obtain money. Her trial is to begin in July.
Porterfield is accused of forging the signatures of three business owners on contracts for advertising with a marketing company at which she had been employed.
Her lawyer told the Journal Sentinel Porterfield acknowledges she made mistakes while trying to make her mandated commission goals but emphasized she did not benefit financially from her actions.
First runner-up Jordan Marie Morkin will represent Wisconsin at the Miss USA competition in Las Vegas, the newspaper said.