Protected partitions, such as the OEM partitions offered by computer manufacturers and used to factory reset your PC, are not always easy to remove. If you try to delete a hidden or protected partition under Windows you will notice that the "Erase Volume" option in the Disk Management is greyed out or you might get the error “Unable to delete a protected partition without the power to delete protected parameter set” in the Diskpart window. In this case, you have to use the parameter "override" to delete the protected partition.
The following steps will guide you to do that. Please pay attention to the fact, that the following steps can harm the operating system. Perhaps it's wise to clone the disk before that.
TLDR: Start dispart, list all disks, list the partition, and delete the correct one with the additional flag override.
- Start diskpart (WIN+R and Type "diskpart" or WIN and type it directly in the windows start menu)
- List the disks: `list disk`
- Select the disk: `select disk x`
- List the partitions: `list partition`
- Select the correct partition: `select partition y`
- Delete the partition: `delete partition override`