bcdedit /import /clean This command restores the state of the system store using a backup data file previously generated ...

bcdedit /import  [/clean]

This command restores the state of the system store using a backup data file
previously generated using the /export command.  Any existing entries in the
system store are deleted before the import takes place.  This command is only
valid for the system store.

          The name of the file that is imported into the system store.
                    If the filename contains spaces, it must be enclosed in
                    quotation marks ("").

    /clean          Specifies that all existing firmware boot entries should
                    be deleted (only affects EFI systems).

Example:

The following command imports the specified file into the system store.

    bcdedit /import "C:\Data\BCD Backup" /clean