How to start a buy out

If the co-owners and you can't reach an agreement on selling your interest to them, you can file a "Partition Suit", which normally ends in a Court-ordered sale of the property at auction, with the net proceeds divided among the owners in proportion to their interests. You'll need a lawyer to file such a suit as there are some technical aspects to it but it's a way to force a sale of the property.  Any real estate lawyer will be well familiar with the process.