Two tenants in our building. Not vacating.

Tenant 1- has been living In our house on an expired rental agreement for 20 years or so without paying any rent. Many attempts were made to collect the rent And draft a new agreement, but they would force us to sell the property to them instead. Currently, the tenants son is living in the property and he too forces us to sell the property to him. We do not want to sell. We have been asking him to pay the old dues and then become a proper tenant by signing a fresh agreement. But he refuses. Question 1- Can I reduce his electrical power by changing the MCB to a lower capacity. ( I know cutting off power supply altogether is illegal). Currently he uses a a very high capacity MCB and the building is very old with old wiring. Doing this, will result in him not being able to use all his fancy gadgets. Only lights And fans and a geyser may work? Question 2- is en expired rentanal agreement transferable from father to son, after fathers death? Question 3- he has done illegal construction and occupied areas of the building which was not mentioned in the original agreement. Can I demolish those additions he has made (he has extended the stairs out of the building compound and blocked our access to the terrace completely). Do I need to send him a notice before I do that or do I as the property owner have the legal right to just go ahead and take possession of the parts that does not and did not belong to them? Question 4 - does he hold the position as a tenant (under law) or can he be considered as a trespasser? Tenant 2- the Residential property was rented out to a bank 20 odd years ago by my grandparents. The bank also has not bothered to renew the agreement, however they had been paying the rent fixed at that time to the account. The account holder ( grandmother) is no more. Their only son, my father has now transferred the property to his name. The bank first asked for the title deed which we provided. Now they are asking for succession certificate. Also they have stopped paying the rent for exactly 1 year now and no one lives in the house either for over 9 months. But they have not handed over the possession of the house. Question 1- when the title deed clearly has the name of the property owner, why then is the succession certificate necessary? Had we sold the property to someone else, they would only have to take the title deed to prove the ownership. Obviously that person cannot give a succession certificate. Question 2- when the bank had stopped paying the rent, and does not want the property, but does not hand over he keys, can I break open the house myself?