Music services often build up recommendations based on your history (and plenty of other sites) and that often means you'll get junk recommendations if you turn over control to someone else for a while. Clearing out that history on Google Plus Music is super-easy.
All you need to do is head to your settings page, scroll all the way to the bottom, and click the Delete button below "Delete recommendation history". This should delete whatever history Google's using to recommend you radio stations and other picks.
Delete Recommendation History in Google Play Music [Google Operating System]