Unable to change default search engine in Chrome: This setting is enforced by your administrator

either you can right click on chrome and run as an administrator or follow the following steps.

Problem: the default search engine in Chrome is locked with a message:

This setting is enforced by your administrator

How to unblock it? 

The search engine change is restricted by group policy.

1. Run the command promt as administrator:

2. Paste each of three strings into console and press Enter:

RD /S /Q "%WinDir%\System32\GroupPolicyUsers" 
RD /S /Q "%WinDir%\System32\GroupPolicy" 
gpupdate /force

Wait until two notifications appear:

User Policy update has completed successfully.
Computer Policy update has completed successfully.

After that you can close the command promt window and try to change the search engine in Chrome:

Make google.com as default and press DONE. enjoy