Consult your engine manual. There should be a drain plug on the side of the engine at the lower limit of the 'block' ... not the 'pan'.
If there isnt a 'drain-cock' already installed there will/should be a 'plug' (with 10mm 'square head') ... remove to drain. Many times due to internal rusting in the block you need to insert a small screwdriver, etc. to clear the rust immediately inside the 'plug' to allow drainage.
Note: I suggest that if your purpose of the draining of the block is for 'winter, etc. storage', that you do not store the engine (block, etc) 'dry'; but, rather fill the block with antifreeze containing suitable anti-rust compounds. Storing an engine 'dry' will promote the formation of internal 'slab rust' of the cast iron - shortening the useful life of the engine. Keeping the internals wet with antirust compounds , will prevent or lessen the internal 'rusting'.