New
#11
The alternative to simply dumping files would be nuking the entire drive and with a 3rd party partitioning program as dalchina has suggested you may even want to consider a totally new fresh primary to work with. That will automatically free up all drive space while you keep all of your important things on another drive at least until 10 is up and running well.
On the other thread I had mentioned the OP decided to restore an existing system image he had made rather then see to a pair of fresh downloads one for seeing a new 10 install key made up with the MC tool and the other to have a fresh "Windows.iso" file tucked away safe on another drive until he got a working Start menu! I told that for clean installs not any upgrade that was still a bit rare at this time.