How do I remove the old OS install on Windows 8.1 machine? I just installed the SSD did the migration (no problems there) but when I went into disk manager it will not let me format the old HDD disk. The only option allowed is to shrink volume....Any help is appreciated.
If everything is working well after the migration, you could try with another partition manager, such as Partition Wizard, which is free. I would create a backup of the partition before formatting it.
