If he has been there undisturbed for more than 12 years then he could be deemed to be the owner of that portion otherwise you have full right and can have him evicted by due process of law.

Best regards

If he has made construction from his own resources, he will be entitled to all the rights.

Suit for possession has to be filed in District Court of the area for ejectment of the person occupying the property. Question of defence of 12 years prescription etc. shall be decided later on by the courts. ownership is based on papers and possession is to be sought.