Can I track my phone if the thief has reset it? My phone was stolen by thief. I called but they obviously had taken out the sim. They've logged out all my google accounts, Twitter, Facebook, Viber, and I think that they did a factory reset! Is there anyway I can track my phone? It was a Redmi Y2.
No, there isn't. There are third party apps that were able to do this with root (unless the thieves flash a completely new rom/firmware). However, you would have had to install that beforehand.

And why there isn't? I think it's for privacy concerns. Basically, Google/Redmi cannot know if the phone got stolen or just sold. So tracking the phone might be in conflict with local law. Also, sometimes the law values privacy concerns higher than simple cell phone theft. Therefor, even in that case it would be against the law to track the phone.

So again: no, it's not possible. Unfortunately, there's nothing more you can do.