The awnser: diskpart.exe! Hit “Windows Key” + “R” to open the run dialogue box and type “diskpart” and hit “OK” to open a command prompt window. Type “list disk”. Type “select disk n”. Type “list part”. Type “select part n”. Type “delete partition override”. Type “exit”. Thanks to http://www.disk-partition.com/blog/how-to-delete-an-oem-partition/