Running in dual boot mode means you can choose between two OS's. First off I must say that it irritates me when people use external hard drives to hold crucial data (such as windows files or even a whole OS) and require them to be connected in order to boot. Why don't I like this? Well, you're running an external hard drive as an internal hard drive through a USB 2/3 port, which slows things down compared to traditional SATA 2/3. If you delete the Windows partition from your hard drive, the Mac OS will not just magically move itself from your external drive. If you really want to have a Mac-only system, uninstall both OS's and reinstall Mac OS on your internal HDD. At least, that's how I suppose it would work. To be honest I don't know jack about hackintosh so that's all on you.