To wipe disk can erase private data completely, and MiniTool Partition Wizard tutorial here shows how to complete this operation in easy operations.

1. How to Completely Wipe Your Disk
About "Wipe Disk"
Wipe Disk can destroy all information in your chosen disks safely and permanently. This
function can ensure the security of your private and unwanted data and prevent someone
from recovering your data. Once the Wipe operation is carried out by Partition Wizard,
the data will not be recovered by any data recovery software. If you use the method of
DoD 5220.28-STD, the data can not be recovered by any data recovery solutions.
--Source from http://www.partitionwizard.com/help/wipe-disk.html
How to Wipe Disk
Step 1: launch the program to get its main interface shown below:

2. Step 2: select the disk which needs wiping and choose “Wipe Disk” from the left action
panel or from the right-click menu.
Step 3: choose one of wiping methods from 5 and click “OK”. Different methods cost
different time and enjoy different security. To be specific, the more time it costs the higher
security it enjoys.

3. Step 4: now we can see the selected disk namely disk 1 becomes unallocated, which
shows it has been wiped. At this time, please click “Apply” button on the top to perform all
changes.