To make a long story short, I created a partition (Drive E) that I no longer need. I would like to reclaim that unused space. How can I do so?
My OS is Windows 8 RC Build 8400; currently downloading Windows 8 RTM.
If you search for partition on the start screen and refine the search to settings, you will find the disk management application.
After starting the application, you will need to locate the unused partition, right-click it and select "Delete volume..." After deleting the unused partition, you can right-click on the partition that you want to give more space to and select "Extend volume..." After that, just go through the steps and you'll be good.
You can delete the unneeded partition and extend the existing partition into the empty space.
You can do this easiest with
Computer Management -> Disk Management
Though if the unneeded partition is earlier on the disk than the current one, keep in mind it will create a Dynamic Partition and have certain restrictions involved.
If you aren't using E: drive as your boot disk. Then you can extend that volume to other drive using DiskManagement and select the disk to which it has to be extended right click on it then extend volume. You can see drives that can be extended.