My name is XXXXX XXXXX I'd be happy to answer your questions today. I'm sorry to hear that this has happened.
A person is allowed to post a statement of opinion on a public review site, even if it's not kind to the person or company that it is about. However, if they are making factual statements that are not true, that is defamation
of character. A business has a reputation just as a person does, and a business can sue for defamation of character.
If you know which tenants are making these postings, you can send them a "cease and desist" letter, explaining that you wil sue if they do not correct/retract the postings or delete them immediately. If that doesn't work, you will have the ability to take them to court for making untrue statements. In a situation where you're not able to identify them from their postings, then the option is to subpeona Yelp to get them to release the user information associated with those reviews.
If your business is incorporated or an LLC, unfortunately, you cannot represent the business in court. That means that you would have a local attorney assist you. An attorney can write letters for you and can also work to get the user information from Yelp.
If you have any questions or concerns about what I've written, please reply so that I may address them. It's important to me that you are 100% satisfied with the service I provide. Otherwise, please rate my service positively so that I get credit for answering your question. Thank you.