Can I create and sell courses that teach Votel, for example on Udemy?

Yes. You are welcome to create training courses about Votel, including on platforms such as Udemy. You can say it is a Votel class and explain that it is white labeled.

The one disclosure you need is for affiliate links: if the course or content uses your affiliate link, you must disclose that you earn a commission, as the affiliate agreement requires. No other disclaimer is required.