Windows 10 Complete Format

Once s system has been activated with Win 10, the license is kept online.  If you are asked for a key just skip it.  It will activate after you are online.

Can you give details about complete formatting laptop and making recovery?? I got windows 10 pre-installed.

Can you share me the steps to complete format and make recovery of system without loosing their license key? I have 5 drive now, 3 is for recovery, system reserved, Windows and two for my file. Can i delete all drive during installation then how can i make recovery drive again. Please share me the steps

The OEM drive has the partition necessary to recover your system.  If you do not care about that or any OEM software, when you install Win 10, you can clean the entire drive or just the critical partitions during the install.

Critical partitions are UEFI, MSR, Small Recovery and OS.  If one of these partitions are left on the drive, Win 10 will not be able to create the partitions it needs in the unallocated space you make available.

Maybe someone else could help you recreate the recovery system but I can't.  I would use a Win 10 Recovery drive or the downloaded image from Dell.

The original license is in the UEFI bios.  But you won't need it.  You originally stated you want to completely reformat your system... have you changed your mind?