Formating the C drive - 2 OS

[Nignags]

I have 5 partitions - of which there are OS on the two of them - a non-functioning Windows 8.1 and a windows 7 pro. W7 works fine but lacks space and I want to format the partition W8.1 is - C - but I do not get the option when I right-click. What to do? Is there a safe software-tool I can use to overwrite the restrictions?

[WAWood]

@Nignags 

Let's make sure we are talking about the same thing ...

When Windows boots, the partition containg the OS is AUTOMATICALLY assigned the letter C:, even if there are other OS partitions present on the same or other drives.

So, let's say you have the following setup:

1) Windows 7 -- booted into it -- shows as C:

2) WIndows 8x -- NOT booted into it -- shows as F:

If you then rebooted, this time, into Windows 8x, it would now show as C: and win7 would then most likely be seen as F:

So basically, you can NOT remove Win8x when you are booted into it; instead, you have to boot into Win7.  But after you do that and you run Disk Management, you should then be able to remove the Win8x partition.

Are you saying you are doing this and getting an error when trying to remove Win8x?

[Nignags]

yep, that's correct - the win 8.1 do not give me the option of format when I right-click on it. The win 8.1 do not work - and I have been strugling whit it - And win 8.1 does not work - I've struggled with it through four installation attempts without success - it continues to fail on windows update where it is just pending without finding anything or update anything. That's why I have gone back to Win 7, and I want to delete win 8.1 so I can use the space. I've added a pic of the divice manager to give you a glance of how the setup is...

[WAWood]

@Nignags 

OK, I see now.

What I recomment is that you try using a third-party tool known as MiniTool Partition Wizard as that should allow you to remove any partitions you desire:  https://www.partitionwizard.com/free-partition-manager.html

Good Luck