ADB root is not working on emulator (cannot run as root in production builds)

Go to tools -> SDK Manager -> Android SDK -- Now In the first tab (SDK Platforms) first of all "select" show package details at the bottom of the page. Now Select "Google APIs Intel x86 Atom System Image" and unselect "Google Play Intel x86 Atom System Image". This emulator won't show "adbd cannot run as root in production builds". Google API's don't have play store app and it only has play services.

You are using the wrong emulator image if you want root access. As the error message states, root is not allowed in production builds, use an userdebug build instead.

To enable root access: Pick an emulator system image that is NOT labelled "Google Play". (The label text and other UI details vary by Android Studio version.)

Exception: As of 2020-10-08, the Release R "Android TV" system image will not run as root. Workaround: Use the Release Q (API level 29) Android TV system image instead.

Test it: Launch the emulator, then run adb root. It should say

• restarting adbd as root

or

• adbd is already running as root

not

• adbd cannot run as root in production builds

Alternate test: Run adb shell, and if the prompt ends with $, run su. It should show a # prompt.

Steps: To install and use an emulator image that can run as root:

1. In Android Studio, use the menu command Tools > AVD Manager.
2. Click the + Create Virtual Device... button.
3. Select the virtual Hardware, and click Next.
4. Select a System Image.
   • Pick any image that does NOT say "(Google Play)" in the Target column.
   • If you depend on Google APIs (Google Sign In, Google Fit, etc.), pick an image marked with "(Google APIs)".
   • You might have to switch from the "Recommended" group to the "x86 Images" or "Other Images" group to find one.
5. Click the Download button if needed.
6. Finish creating your new AVD.
   • Tip: Start the AVD Name with the API level number so the list of Virtual Devices will sort by API level.
7. Launch your new AVD. (You can click the green "play" triangle in the AVD window.

[Credit belongs to @Merk but this should be posted as an answer rather than a comment.]