If you need to wipe an entire computer or multiple drives, DBAN is a free, open-source bootable tool that is arguably more powerful than HDDGuru for total data destruction.
To obtain a license code for HDDGuru Low Level Format, follow the given steps: hddguru low level format license code
It is functional but throttled to a speed of 180 GB per hour (50 MB/s) . If you are wiping a modern 4TB or 8TB hard drive, this process can take an entire day. If you need to wipe an entire computer