Hide sql database after installing Winform Application

You can never hide it properly. Any user with a little Windows knowledge will be able to work around that. If your users run with admin privileges, you're also out of luck because they can change any settings.

The only solid way to prevent abuse and secure the information is to use encryption / decryption. Store the data in encrypted format or encrypt the complete database. The first option can be used if you only need to access the data via your application (data to be encrypted /decrypted by application). The second option can be used if multiple applications use the database (e.g. your application and SSMS).