How To remove a partition from an external hard disk?

Make sure that the drive is attached to your PC and powered on. In other words, make sure that your system recognizes your external drive.

Next "Right Click" on your "My Computer" icon and choose "Manage" from the drop down menu. This will open the Management Console. Next, click on "Disk Management" which will be located near the bottom of the left pane of the management console. When the disk management console appears find the external drive in the drive listing and click on it. The partition will become

highlighted in blue to indicate that it is selected. You can then right click on it and select "delete partition" from the menu that opens up. You can also create a new partition the same way if you'd like.

Good luck,

Sources: http://www.noblepassmercy.blogpsot.com