Sources suggest there is no specific function to hide best friends on Snapchat. However you can block and delete friends here.
Best friends are updated on a weekly basis and represent the friends you chat with most frequently. They are selected automatically by a magical Snapchat friendship algorithm.
Of interest, researchers say that hackers are using Snapchat to freeze iPhones. Snapchat has been notified of the vulnerability. If you become aware of any security issues with the app contact the company by emailing firstname.lastname@example.org. Learn more from the Los Angeles Times.