You cannot opt-out of allowing staff to read your notes altogether, but you can export your data and move to another service.
If you don't need OCR and are on Mac/iOS, I have found Bear to be a great note-taking alternative to Evernote.
It includes Markdown support, code syntax highlighting (for some languages), and Evernote migration:
http://www.bear-writer.com/faq/Code%20Snippets/Show%20code%2...
http://www.bear-writer.com/faq/Import/Migrate%20from%20Evern...