The co-owner has committed the offenses of mischief and criminal trespass. You should file an FIR against him, as he has no right to demolish the common wall that was erected in compliance with HSVP regulations. If the co-owner has any grievances, he should make a complaint before the appropriate authorities of HSVP. However, instead, he has taken the law into his own hands and demolished your wall. His act constitutes an offence.
You should also initiate a civil suit to recover the losses you incurred due to the demolition of the common wall, as well as to seek a permanent injunction. A decree of permanent injunction would prohibit the co-owner from interfering with the premises. You may also claim litigation expenses and compensation for the mental agony you have suffered due to the demolition of the wall.
