To update your system to the latest version, there must be enough disk space for the update files. Windows tries to automatically use another device if your system operation is full, but with some steps you can also force Windows to get updates elsewhere.
By default, Windows stores all updated downloads to your main device, this is where Windows is installed, in the C: Windows SoftwareDistribution folder. If the system drive is too full and you have another device with enough space, Windows often tries to use this space if it can. Windows takes care of deleting update files at some time after they have been installed, but often, especially for major updates such as the October 2018 update, they hold these files for a while if you want to uninstall the updates or roll back your version of windows.
Because these updates often take up much space, 16-20 GB in some cases, you may want Windows to download them to another device, especially if you're using something like a solid state device where disk space is top . You have to jump through some hoops to make it work. We turn off the update service by using the command prompt to create a symlink (a virtual link to a new folder so Windows still believes it uses the original folder) and then restart the update service. However, it is not complicated, and we go through the steps.
Note! Before you go anymore, you should back up your computer only if something goes wrong when you change things in system folders. (You should really back up regularly, anyway.) It's a pretty safe process, but better to be safe than sorry.
Step One: Create a New Update Download Folder
The first thing you do is create a new folder for downloads on another device. This is where Windows will store any future update downloads.
In File Explorer, locate the location you want to use, right-click anywhere, point to the "New" submenu, and then click the "Folder" command. 
Next, name the folder to what you want. We have named our "NewUpdateFolder", and it is located on the D: drive.
Step Two: Stop Windows Update Service
Then you must stop Windows Update service to prevent it from updating when you change things around and because in the next step you will rename the old one updating the folder. In the Windows Update service, you can not do it if it is running.
Press Ctrl + Shift + Esc to open the task manager and click the "Services" tab.
Scroll down until you find the service
wuauserv near the bottom of the list. Right-click it and then click "Stop."
Step Three: Rename the Old Download Folder
Now you need to rename the existing folder to something else. This is because you create a new symlink folder, and Windows does not allow you to have two folders of the same name, even if you just point to the new folder you created in step 1.
In File Explorer, scroll to
C: Windows . Right-click the "SoftwareDistribution" folder there and then click the "Rename" command. You will be asked to get permission to do this; Click "Yes".
The easiest thing to do is just keep "Old" on the front or back to indicate that this is not the current folder we are going to work with. If you are prompted for permission again, click "Yes".
Step Four: Create a Symbolic Link to the New Folder
Now that you have created the new folder you want the downloads to go and rename the old folder "SoftwareDistribution" to get out of the way, you need to show Windows how to find the new folder. To do this we use what is called a symbolic link or symlink. These act in the same way as a shortcut does; they point to a real folder somewhere else on your computer.
First, run Command Prompt as an administrator. Click Start, type "cmd" in the search box, right-click the "Command Prompt" result, and then select the "Run as administrator" command.
Type the following immediately by entering the following command (replacing "d: NewUpdateFolder" with the entire path to the folder you created in step one).
mklink / jc: windows SoftwareDistribution d: NewUpdateFolder
After executing the command, you should see An answer that indicates "Link created for" followed by the paths you specified.
A new "SoftwareDistribution" article with a shortcut icon is added to the
C: Windows folder.
Note! : If the command
mklink did not work or if you encountered an error, try restarting the computer to Safe Mode and repeating previous steps.
RELATED: How to boot in safe mode on Windows 10 or 8 (the easy way)
Copy the contents of the old folder "SoftwareDistribution" rename in step three) to the newly created symbolic link. This prevents Windows from retrieving any updates.
We suggest you copy instead of moving content for now only if something is not working. Once you've checked that everything works, you can always come back and delete the old folder later.
Step Five: Launch Windows Update Service Again
The final step is to start Windows Update Service backup.
Open the task manager by pressing Ctrl + Shift + Esc and switch to the "Services" tab.
Scroll until you find the service
wuauserv near the bottom of the list, right-click it and then click the "Start" command.
Hereafter, when Windows Update retrieves files, they will be stored in the newly created folder.