If you want to use tools like Facebook, Twitter, Yelp, etc. to publicize your business, then you have to accept that you will get negative comments. If you do not have the personality that can bite your tongue, apologize sincerely, and offer a discount or other consideration for anyone claiming bad products or service, then the answer is to just not play on social media. The internet is absolutely an environment where the customer is always right.
Most sites do not let you filter comments. Even if they do, any attempt to delete them will just lead to more vitriolic responses. The good news is that internet users are very experienced with spotting trolls who are just trying to pick a fight and hear themselves talk. Just continue to respond positively and feel confident that your good services will be endorsed enough to easily offset the few complaints.