Java DB is a relational database management system developed by Oracle. It is based on Java programming language and SQL. It helps you create, configure and manage databases. If you don't need the program, you can safely uninstall it (Control Panel > Uninstall a program). If the standard uninstalling process is not working you can try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.