What can we do about a non-paying apartment member?

I live in an apartment in Hyderabad. One of our flat members is not paying the monthly maintenance fee and is threatening us with legal action if we ask him to pay. The issue is that our apartment is not yet registered as a society. Taking advantage of this, the person is influencing others not to pay. However, to avoid penalties from the government for the water and electricity bills, we are voluntarily collecting the amounts and paying the maintenance fees. This person is making a mockery of the judiciary, often saying, "I worked as an advocate, I know the law. I can file a case against you. You all must consult me and take my advice for any decisions, and you must come to my home for advice." Please guide us on how to resolve this issue.