Getting back to "raw" drive

I was recently trying to add a SSD drive to my grandson's computer, trying to clone the existing hard drive to this new SSD drive. The system recognized the drive, I started the Toolbox and selected the Clone option. It displayed the partitions on the old physical drive and seemed like it should clone to the new drive with no problems. Over 3 hours later, this was only at around 23% done, which this is a new install of Windows 8.1 on his system, just bare bones so I didn't think it should have taken this long. Very slow. Doing some research, I found that there was a setting I should have set in BIOS, AHCI (?) so I stopped the cloning, set this in BIOS, and then rebooted the computer thinking it would allow me to start over. It does not, saying my drive was not clean or un-used so I could not start over. Hopefully a simple question, how do I get this drive to go back to a "raw" condition? I had seen a utility to wipe the drive but I thought that might just be for data only and I just did not want to mess this up worse than it already was. One other question, should it have taken this long or did not having the correct setting cause it to take this long? Maybe I just should have been more patient. This was my first attempt to use an SSD drive and sometimes us old techs just don't get it right the first time.

Thank you.

I'm surprised the system was able to boot after changing the setting to AHCI (unless it was RAID before, in which case changing it did nothing). Windows is actually very particular with ATA vs AHCI so if you install it with one mode you have to change a registry setting to change it in the BIOS and allow it to boot.

You need to secure erase the drive. Gparted Live or Parted Magic can do it for you.