Hello, my name is XXXXX XXXXX it is my pleasure to assist you with your question today.
Do you mean take action against them outside of the workplace?
That will be rather difficult I'm afraid. You are really looking at claims such as defamation, and these are very complex and expensive. They will inevitably run in the thousands and you have no guarantee of success and even if you win you cannot guarantee that those responsible will be willing or able to pay any compensation you are awarded. I would certainly not recommend you get involved with such claims.
This is really an employment matter where you are able to raise this as a complaint with your employer and they will investigate this and consider whether any action is appropriate. This would most commonly include disciplinary action against the guilty parties, although it is for the employer to investigate the allegations and decide on what steps are needed to be taken next.
You are able to take this matter further by raising a formal grievance to the employer and including details of these posts. I suggest you print or save these comments before they are removed so that you can use them as evidence.
Please let me know if this has answered your query or if you need me to clarify anything else for you in relation to this?