you must Go with a name in which you can register with Trademark Laws.
I'd utilize a business name generator, mix it with some of your own creativity / puns / plays on words around window cleaning and janitorial work and then lastly be sure you can get the domain / the name doesn't exist in your area before you settle on one!
You may check with a good number of those you trust to pick the best one. Usually, it should be something that's catchy but also meaningful to your business.
You may use business name generators.