Good question! But also not a simple question since there are a lot of ways to answer it.
You could start by educating this Sponsor/Champion on Lean Six Sigma basics. You could send them a link to either the White Belt (1 hour) or the Yellow Belt course (8 hours) which are both free and make a great case for the benefits of process improvement. There’s a great article about what it takes to be a good Champion/Sponsor that could also help. You might take a look at some sample success stories and find the ones that most relate to the type of business you’re in and share those with your Sponsor. All of this information, and a lot more, is in the Rollout Kit (coming soon) which is a guide to bringing Lean Six Sigma Training into the organization. That should give you a good start.
Please reach out again if there’s anything else we can do to help!