Hi Leslie :cool
You should have no problem cleaning your electric lawn mower for shipping. Buy some Jeyes Disinfectant Fluid and clean it up.
You'll eventually need to fill out a declaration regarding items you're importing (usually supplied by the removal company). Enter the mower on that form and state how it was cleaned and you shouldn't have any problems.
Remember they are looking for any kind of bugs or other nasties that could invade the counrty. If it's clean and shiny, they'll be satisfied. Make sure to get every bit clean though...grass and such gets into the oddest places!
You'll just need a mains adapter or you can cut the plug off and put a NZ style one on and you'll be in gardening business.