Eclipse try downloading a free program called C-Clean which will competely sanitize your hard drive. Use the option to clean white space. That should be as effective as melting it without destroying it. Make sure you set the option before you start.
In general when one deletes data, it leaves it there, and just puts a question mark into the first letter of the file. It looks deleted, but the info is still there. Undelete programs can recover. However, if you use a program to clean white space, it will actually erase and overwrite the data. Various standards call for repeating this 3 or even 7 times to make sure it is competely gone. You can set the choice of standard in there as well.
The old Norton Desktop also did similar things, I think.
If C-clean is not what you want, there may be other better programs out there, as well.