Steps to Rename Your Package in One Go:

1. Refactor Directories: Right-click on the package → Refactor → Rename → Choose to rename all directories.

2. Update Gradle File: Open app/build.gradle and update both the namespace (in android) and the applicationId (in defaultConfig).

3. Check Manifest: Ensure the package attribute (if specified) in AndroidManifest.xml reflects the new package name.

4. Clean & Rebuild: Clean the project and rebuild to apply all changes.

If that didn't work, check this detailed solution on StackOverflow.