Looking for advice on how to present data that won't go down well

I've been conducting usability tests for a start up who wants to change their main product to be a lot more streamline. From the beginning,their idea of how they wanted to change their product sounded like a bad one to me. Now, after conducting some tests and interviews, I've the data to back it up. The thing is though that the company is set on doing this, they just want to work out the kinks. Whereas my data shows people would stop using their product. Is there any trick on how I can deal with this without being "the messenger"? This is my first time doing UxR and I'm very grateful they gave me this opportunity. I don't want to mess it up.