Homeowners Insurance is not a legal requirement as long as you own the home outright and don't owe a mortgage on the home.
If you're buying the home through a mortgage then the bank requires you to have homeowners insurance on the home and if you fail to keep homeowners insurance up on the home then the bank can foreclose on the home and force you to move out.
Sometimes the homeowners insurance is carried through the bank and mortgage so you may already have homeowners insurance on the home without really knowing about it and part of your mortgage payment could be going toward the cost of the homeowners insurance.
If you own the home outright and have no mortgage on the home then yes you're free to go without homeowners insurance.