It seems Microsoft Edge on Windows 10 Mobile will soon allow changing of default search engine from Bing to Google or others. Two leaked screenshots from an unreleased Windows 10 Mobile build reveal this.
The feature has been present on Windows 10 since long and we have posted our tutorial with hands-on video demo of how to change search engine on Microsoft Edge. Now looking at the screenshots above it seems the process may not be different in case of Windows 10 Mobile too.