How to convert OS HD to Storage and maintain all files

First, there is no need to boot from a USB flash drive to remove old system files from the old hard drive once plugged into the new computer. Most of your files will be in the \Users folders. The first time you go into \Users\<username> on the old hard drive, Windows will tell you that you need administrator permission, just click yes to give permission. See if all the files that you want to keep are in the \Users folders. You probably won't have any user files in the Windows folder so you can start by deleting that one (it will take a LONG time to delete all those files). You also can probably delete the Program Files and Program Files (x86) folders.

Also, @ToLongPong, since you stated that you wanted to keep your old files, do NOT follow the advice to format the drive as you will lose all those files that you clearly stated you wanted to keep.

Since you have a new drive installed, though, why can't you just copy your user files you want to keep to the new drive and then reformat the old drive?

Finally, there will be other partitions on the old drive that you will no longer need. You only need the partition with the user files in it. You don't need system or recovery partitions. Using a program such as Minitool Partition Wizard Free you can delete the unneeded partitions and expand the remaining partition to fill the empty space.

Best Free Partition Manager for Windows | MiniTool Partition Wizard Free

What I have done in a similar situation is to use MiniTool Partition Wizard free to remove all unneeded partitions, shrink the remaining partition with the files in it to it's smallest size and move it to the beginning or end of the disk. Then I create a second partition in the remaining space. Move, not copy, the files you want to keep from the old partition to the new partition. If you need to keep resizing partitions because you run out of room on the new partition you can keep resizing them as you go. After a month or so when you are sure you have all the files you want to keep in the new partition, just delete the old partition and expand the new partition to fill the empty space.

I wish to convert a HD with OS to Storage and keep exsisting files

I use a filesystem driver that ignores permissions.

First MOVE anything in other HD users\your-username that you want to keep to the root of the partition ( photos, documents, downloads, videos, whatever you want to keep )

Next, to delete what you dont want:

It might be simpler for you to use dism++ file explorer. Use it to browse to the other HD and delete the windows namespace folders:

PerfLogs
Program Files
Program Files (x86)
ProgramData
Recovery
Users
Windows

and:
hiberfil.sys
pagefile.sys
swapfile.sys

Do not delete the Documents and settings link

Personally, it seems like deleting Users would be a bad idea, to me.

Why? The Op said he doesnt want it. As long as he moves out the stuff he might want first.There is often a load of unwanted junk in Users. If you want to transfer the browser settings or email client stuff to a new installation, just move it out of the old Users\username - e.g.
"Appdata\Roaming\Thunderbird"
"Appdata\Roaming\Mozilla"
As well as anything from documents, or photos, etc you want to keep.


I have done it several times.

SIW2 said:

Why? The Op said he doesnt want it. As long as he moves out the stuff he might want first.There is often a load of unwanted junk in Users. If you want to transfer the browser settings or email client stuff to a new installation, just move it out of the old Users\username - e.g.
"Appdata\Roaming\Thunderbird"
"Appdata\Roaming\Mozilla"
As well as anything from documents, or photos, etc you want to keep.


I have done it several times.

The OP stated:

ToLongPong said:

I wish to convert a HD with OS to Storage and keep exsisting files.

Plan to add this as a second harddrive with my old files still on it.

It does not sound like he wants to move files off the old drive, it sounds like he wants to keep the data files there. If he deletes the Users folders he is going to delete all of his user files, almost as bad as formatting the drive, but not quite. If he deletes the Users folder, he might as well reformat the drive because most of his data files such as documents and pictures will be deleting with the Users folder anyway.

Precisely.

MOVE any files you want to keep from the users folder to the root of the partition ( or drive as you call it).

Then delete the windows namespace folders.

The files/folders that were moved to the root are still there on the same partition/drive.

SIW2 said:

Precisely.

MOVE any files you want to keep from the users folder to the root of the partition ( or drive as you call it).

Then delete the windows namespace folders.

The files/folders that were moved to the root are still there on the same partition/drive.

True. Good point. There is benefit to that for sure.