I have two SSDs both of which are mounted on separate "C" Drives.....W8.1 on one and W10 on the other.
To create extra space on W10 have decided to format the W8.1.
Have tried changing the drive letter in W8.1 so that I can open with W10 in order to format W8.1....drive letter change not possible, format greyed out.
Neither M$ Disk management or CCleaner could perform this task.
Any ideas would be appreciated.
It shouldn't matter, the win 10 OS when booting will assign drive letters to both, and the one that it boots from will be C:
Boot it up with your 10 and the extra ...
I can boot up separately with each but when I connect the two together it only recognises W10.
What does disc management show for the extra drive when booted into 10?
You should be able to reformat, allocate space, etc.
As stated already extra drive W8.1 does not appear when booting from W10.
I must emphasise I only wish to format W8.1.
Have you tried booting into safe mode with command prompt on the Windows 8.1 drive and run a format command?
Reasoning on my part suggests you cannot remove an O/S while it is operational.
Have finally solved the problem, or rather M$ solved it.
As already stated each SSD worked perfectly on their own.
After trying to get either to recognise the other.....at the third attempt Windows started to correct faults on W8.1 then started to correct faults on W10.....from there it was easy to change the disk letter on W8.1 to "E" then restart the computer with W10 to format W8.1.
My Thanks to all who replied.
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