Do you see the Powershell in Programs and Features in Installed updates?
If you see that installed in there then, follow the steps mentioned below.
Try to remove it from Installed Updates:
on “Control Panel” in “Start menu”
to “Uninstall a program” in “Control Panel”
on “View installed updates” in “Programs and Features”
click on Update which reads Powershell and uninstall it.
Note: This section, method, or task contains steps that tell you how to modify the registry.
However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs.
For more information about how to back up and restore the registry, click the following link.