I recently upgraded and currently I have 2 instances of Windows (1 in my HDD and the other in my newly bought SSD). Obviously I want to remove Windows 10 from my HDD. Will doing that using OS-Uninstaller format only that part or the will it format the entire disk? I don't want to lose my data.
OS-Uninstaller does not uninstall any other operating systems except for the OS that is selected to be uninstalled, but if you choose to uninstall an OS it will remove everything on that partition including the data. If you want to save any of the data that is stored on that partition then back it up before you uninstall the OS that is on that partition.
If you tell OS-Uninstaller to uninstall the Windows 10 that is installed on the HDD it will not uninstall the other Windows that is installed on the SSD. If there are multiple partitions on the HDD OS-Uninstaller will not delete any other partitions on the HDD except for the partition on which Windows 10 is installed.