Problem you can not delete or change files in WinPE 8.1
Solution:
"Also, here is my step by step process for reclaiming the right to delete and move files.
Note: DO NOT change the permissions of the Windows folder using the following method. Should you need permissions to edit files in the Windows folder, change them individually. Windows Backup can be irreparably (as far as I know) broken by such a change. LEAVE THE WINDOWS FOLDER ALONE UNLESS YOU KNOW EXACTLY WHAT FILE YOU NEED ACCESS TO.
1) Click the start menu and open Computer.
2) Click on the drive that contains the file you are trying to move/delete.
3) Right click on the folder that contains the file you are trying to move/delete. Select Properties.
4) Click on the Security tab.
5) Under the box containing the permissions each entity has, click on Advanced.
6) In the new Advanced Security Settings window, click on the Owner tab.
7) In the owner tab, click on the Edit button.
8) In the new window, you should see "Current Owner:" over a box with (most likely) trusted installer in it. Under that you should see "Change Owner to:" followed by a short list of possible owners.
8a) If you see your username (listed as [Name] (My-PC\[Name])), then click on it and check the box below the Other users which says "Replace owner on subcontainers and objects".
8b) If you do not see your username, click on the "Other users" button. From there, enter your username into the space provided and click Check names.
The username you typed should then get underlined and expanded. Then click Ok. From there follow step 8a.
9) Click Apply.
10) Now close all windows opened from the properties window and close the properties window. Reopen it, and under the box entitled "Group or user names," Click Edit.
11) If you do not see your username, as chances are you won't, click add. In the add window, type your username into the given space and click the Check names button.
Your username should become underlined and expanded to include the computer name. Then click OK.
(I typically just click OK but if for some reason it doesn't work for you, at least you will know at what step you were tripped up.)
12) Upon clicking OK, the Select User or Groups window will close and you should see you username has joined the other names in the Group or User names box.
Click it, and then check the "Full Control" check box lower down. This will grant you complete permissions for everything except "Special Permissions".
This is normal, and so far I have not found a way to check that checkbox but it hasn't presented itself as a problem yet so I wouldn't worry about it.
13) Click Apply. You should see a window pop up saying "Changing Permissions" and file locations rapidly going by. This is normal and it means that the folder, subfolders, and files are having their permissions changed.
Alternatively, after closing and reopening the properties of the folder you want to change, you can click on the Advanced button again and then the Change Permissions button
and follow similar steps once there. This also allows you to create inheritable permissions.
That is a whole new can of worms that I don't understand, so I just leave the checkboxes blank.
AGAIN, DO NOT CHANGE THE PERMISSIONS OF THE WINDOWS FOLDER. THIS COULD CAUSE A WHOLE HOST OF NEW PROBLEMS, ONE OF THEM BEING BROKEN WINDOWS BACKUP.