If you don't want the virtual hard disk any longer, all you have to do is delete it. You don't give specifics, so I will have to guess.
If this is a virtual hard disk used by a VM you tried to create in Hyper-V, first go into Hyper-V and delete the VM. That just deletes the VM - not the disk. After deleting the VM, there should be no process using the virtual hard drive, so you
just have to delete it.
Another thing you might have done is to create the VHD and mounted it to Windows 8. In this case, you can't delete it because Windows 8 owns it. Start computer management (compmgmt.msc). Go to Disk Managment. Find the entry for your
VHD. Right-click and detach it. Then you can delete it.
If it is not one of these things, you are going to have to give a more complete description of your environment and what is preventing you from deleting it.