Maruti Suzuki 800 is a 3 cylinder or 3 piston petrol engine. If I remove two pistons from the crank and block the intake manifold of those piston inlet, will my engine still work on a single piston which in located in the middle crank shaft?
tl dr: Would it run? Possibly Would it have enough power/torque to move your vehicle? Not a chance.
There are several things with trying to run the engine this way.
Every internal combustion engine has a balance applied to it so it can run relatively smoothly (there are some exceptions). All of the bits/pieces are used together in harmony to create this balance. By removing the pistons/rods on the outside cylinders, you've completely thrown the balance of the engine out of whack. This would most likely cause severe damage to what's left of the engine (bearings and such).
2. Engine Monitoring
You'd have to shut down engine monitoring and fuel to the two other cylinders. This would take a pretty good tuner to make it happen. A completely engine remap would be in order.
Some how you'd have to keep the exhaust and intake valves closed on your "missing cylinders". If you don't account for these, you'll run into issues with these ports affecting the flow from the other ports (ie: exhaust pressure reverting into the open cylinders while exhaust is open; intake flow disruption in other cylinders while intake valve is open).
4. Oil Pressure
Crankshafts have holes in them for oiling the rod journals. These would need to be plugged somehow to prevent a huge oil pressure loss, which would drastically reduce the longevity of the rest of the engine.
What I've posted already affects how the engine might run. The biggest issue which you'll run into here is the amount of power you'd have while trying to continue to run the engine. While it may be enough to run the engine (with huge amounts of vibration), you won't have any appreciable power to actually do any work. If you expect to run your vehicle the same as what you did prior to removing the pistons, you have to realize the engine really doesn't have a lot of power to begin with ... it is, after all, just a three cylinder engine (I'm guessing it's an 800cc displacement?). By cutting your pistons down to 1/3 of original, it's not like you'll have 1/3 the power/torque. You'll actually have less than that. This is due to parasitic losses and rotational mass of the crankshaft. I cannot tell you exactly how much, but it would be less than 1/3.
With this in mind, I have no clue why you'd want to do it. Would it be possible to run ... maybe, with heavy modifications. Would you be able to do anything with it? By my thinking, not a chance.