Is there a way to run Eraser from a USB thumb Drive or a floppy drive? I want to erase the C: drive in a couple of computers that I am finally giving away. I am not going to install any operating system. Thanks
You can't, and for your purpose there would not be much point, as Eraser needs Windows to run.
The only options that I know of are:
Use DBAN; details are in the companion forum and also in the DBAN page on Sourceforge; DBAN is not supported and has not been updated for several years, but will probably still work on older machines;
Remove the drives from the machines, connect them in a suitable USB caddy to another machine, format them there, then use Eraser to format the free space;
If the machines are laptops or branded desktops, there may be a utility (using restore disks or a restore partition) to revert them to factory condition; if there is, use this option and then use Eraser to wipe the free space.
None of these is ideal; if you are reasonably experienced, DBAN is probably the best option, always provided that it works.