Trump claims it's because he didn't wait his turn.
Donald Trump removed Univision reporter and Mexican-American Jorge Ramos from his press conference last night in Iowa. Trump claimed it was because Ramos did not wait to be called on, which didn't sit well with the other reporters because that's not how press conferences work. Reporters have to be aggressive to ensure they're seen and heard, and Trump's instant remark that Ramos should "go back to Univision" indicated that he knew exactly who Ramos was and simply wished not to speak with him.
His response would be the same if a reporter sneezed, and he had one of his large goon bodyguards escort the troublemaker from the room. Ramos has unsuccessfully attempted to secure an interview with Trump for months, so he may have had better luck by disguising himself with someone hiding on his shoulders wearing a trench coat.
Ramos was allowed to return to the press conference, and Trump took multiple questions from him over the course of several minutes. In the end, real recognized real, because Ramos is known for his confrontational style of reporting just as much as Trump is for his brash style of answering questions. At the end of the exchange, Trump told him they'd speak again, so we have that to look forward to in the future.