Hi,
Well, in my opinion the best and easiest way to do so would probably just connect it to another computer as a slave drive or simply just another secondary drive. Then you can use a variety of third party applications to perform the task. If you have windows, you can use the built in windows tools to do a complete format of the drive. However I do not recommend it, if you are going to be selling the drive, for security purposes, I recommend you download a third party application such as EASEUS Partition Mananger or Free Partition Mananger Home Edition and perform a format via those programs, because they provide features that enable you to do a secure format, zero filling, overwriting...etc. This is to ensure no data is left on it.