7. Will formatting a hard disk remove data permanently?

Formatting the hard disk does not make it 100% unrecoverable data.  To delete data permanently, a program like (Data Black Hole) should be used.  Or there is hardware methods like below:
- Degausser: A method that uses a powerful magnetic field to erase the hard disk platter so that the magnetic component becomes unrecoverable.
- Crushing: A method that by crushes the hard disk platters, making it substantially impossible to recover
- Dissolution: This method due to the environmental and safety issues needs to follow exact methodology.  It basically puts the hard disk into the furnace and converts it into raw material.