One of the lesser known things is this. In two areas deletion of ANYTHING can get you in tribble with ye old laws.
Safety and emissions.
So I'd not recommend deleting anything.
Regarding the warranty: Do no know why re-titling with same owner but in the USA would void. Suggestion is. If you need warranty work, Contact a lawyer for advice. Not sure if you need a Canadian or US lawyer.
Finally.. No I won't ask why you are moving to USA, from Canada, for an RVer it actually makes sense. I'm from Michigan (The only state other than Alaska where you go SOUTH to enter Canada) in fact from Detroit (The very city where you do that) and I know how hard it is to stay "in state" for six months a year. As the weather changes... More and more tempting to spend 7-8-9 months here in the more temperate south and ony head back to MI in June/July/Aug when you can fry an egg on the sidewalk without a campfire.