My mobile phone number was maliciously marked as a real estate agent. How to cancel it? Please help me.

You should be talking about sending you false advertisements online and harassing phone calls every day, right? I don't think this can be cancelled in the business hall. You should download 360 or other software with a blacklist of incoming calls and set it to refuse to answer strange numbers. Then you'd better find the webpage advertised by the other party, try to complain and ask the customer service staff of the website to help you solve it. There is no other way.