Hard Disk Monitoring

It is possible to permanent change the "Power On Time" smart parameter and make from the old disk a "new" one ?

Of course NOT.

By using the Offset in Hard Disk Sentinel Pro, it is possible to adjust any self-monitoring S.M.A.R.T. attribute (like the power on time) but it's virtual only.
So when you place the hard disk to a new system, the original power on time value displayed, it is not possible to make a "new" from an old hard disk drive.