Whether you are intentionally omitting the word to protect somebody’s identity (such as in legal documents, for example) or you are deliberately withholding the word for another reason (such as cursing or something similar) then we use either two or three em dashes to represent that something has been omitted. You should pick one that is best for you and stick to the same style throughout your writing, because this keeps things consistent. Here’s how it might look:

• “The thief told me to —— off,” the juvenile witness, ——, told the court.