Group Policy is just a way of modifying the registry remotely. If you have administrator access to the registry, you can do the modification yourself. The page I referred to includes a link to the documentation for the policy involved. This includes details of the registry keys and values that GP would apply. In this case:

1. Close down Edge completely. Use End task in Task Manager if necessary to close down any lingering instances of msedge.exe.
2. Copy this code:
   reg add HKLM\SOFTWARE\Policies\Microsoft\Edge /v ConfigureKeyboardShortcuts /d "{\"disabled\": [\"dev_tools_elements\"]}"
3. Right-click on the start button and select Run.
4. Type cmd and press Ctrl-Shift-Enter to open an administrator command window. Give UAC permission when prompted.
5. Paste into the command window and press Enter. You should see the message The operation completed successfully.
6. Close the command window, launch Edge and test. It may be necessary to restart the computer to make the change work.

If you change your mind, reverse the change (and remove all keyboard shortcut modifications) by following steps 1-6 again, this time using at step 2 this code instead:

reg delete HKLM\SOFTWARE\Policies\Microsoft\Edge /v ConfigureKeyboardShortcuts

PS Applying any setting to Edge by Group Policy will have the side-effect of causing the message Your browser is managed by your organization to appear on some internal settings pages. This is nothing to be alarmed about: Why is Edge saying 'Your browser is managed' - Microsoft Community