You can edit Disk System Records (MFT, Boot sector etc.) by using specially designed forms.
To edit Partition Table:
1. In Recovery Explorer or in Partition Manager select a Physical Device
2. In Partition Manager select a Physical Device.
3. To open the Edit Partition Table dialog:
4. Change desired fields to appropriate values
Saving incorrect values might render the partition useless. You may not undo changes that you make in this dialog.