What is the easiest way to...?

You should coat the inside of the rabbit hutch in non toxic varnish to stop the wood soaking up pee, that helps in the long run. Other than that, there's no easy way. Use newspaper under the bedding so you can just pull up the corners and tip into the bin, then clean the corners out with a paint scr, spray on some animal safe disinfectant, leave to dry and then pop fresh stuff in. Litter training the bunny can help, it means less cleaning. Or just clean the dirty corner every few days (if the rabbit has one corner that is) and then do the whole hutch less often.