[edit] Tools Needed

1. Chain splitter/Chain tool
2. Old Rag

[edit] Method

Sit the chain in the chain tool and rotate the arm until contact is made against the pin on the chain, apply pressure to push the pin out. You do not need to push the pin out all the way to split a chain, pushing it out until the pin is at its furthest point will mean you can break the chain and also put the chain back together easily because the pin is still inserted very slightly. It may be useful to use a old rag whilst handling the chain as there will be alot of oil going onto your hands, oil is resilient to water and can be very hard to wash off.