Savin C4535 hard drive overwrite

[Motormount]

Would any of you fine techs know if this Savin C4535 will work properly if I pull the hard drives and overwrite them with Active KillDisk, and then reinstall them? I have read here that installing new drives, the machine will format them as necessary. Would it also work with this approach? Also, should there be any file system or partitions on the disks when reinstalled? Seems new disks would have neither.
Thanks for your wisdom.

[miro]

Why you want overwrite them, in SP mode you have format hdd, dont need any file system or partitions on hdd (it is not canon).

[Motormount]

Data security - the machine is returning to leasing company.

[miro]

The best solution is,old hdd leave to customer, buy new one in local shop and put in