Suppose you want to change the path of default iCloud location in Windows 10 to point to different partition where you have more storage space. Below guide will provide step by step instructions on how to change the path of default path.

  1. Make sure your iCloud backup is turned off from the iCloud app.
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  2. Delete current iCloud Photos folder from C:\Users\UserName\Pictures\
  3. Re-create iCloud Photos folder in C:\Users\UserName\Pictures\

Reason I am recreating folder again is because when iCloud app is installed it has a hidden file that doesnt show up after you change view to show hidden files. To avoid failure of below command to link to external path. I just deleted and recreated the folder.

  1. Create a link of the folder path to point to external drive or external partition.
mklink /J "C:\Users\USERNAME\Pictures\iCloud Photos" "E:\iCloud\Photo_Backup"

Replace USERNAME with your own username.
Above command will create a folder link in your pictures folder that will point to E:\ path.

C:\>mklink /J "C:\Users\USERNAME\Pictures\iCloud Photos" "E:\iCloud\Photo_Backup"
Junction created for C:\Users\USERNAME\Pictures\iCloud Photos <<===>> E:\iCloud\Photo_Backup
MKLINK [[/D] | [/H] | [/J]] Link Target

        /D      Creates a directory symbolic link.  Default is a file
                symbolic link.
        /H      Creates a hard link instead of a symbolic link.
        /J      Creates a Directory Junction.
        Link    Specifies the new symbolic link name.
        Target  Specifies the path (relative or absolute) that the new link
                refers to.
  1. Once Above steps are completed go ahead and click on check box for Photos to start backing up to external path as shown below:
    Click on Photos check box
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    New popup will open:
    Click on iCloud Photos and Shared Albums check Box and click on Done
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    Now in iCloud main photo app click on Apply.

This will automatically start creating photos folder in iCloud Photos and you will see folder getting synced with files.