What bike?
Generally, the chains are "endless" and the crank must be removed to replace it.
Alternatively, there are masterlinks available that allow you to cut the old chain, thread the new one thru, and connect with the master link. The link is a "peen the pin" style and requires some technique to fasten it, or a special tool.
I only know CB750s so will stop till we hear what you are working on.