Yes, you can remove your old town hall from your Google account.

1. Open your Android device, of course.
2. Open Google Settings.
3. Open Connected Apps then tap to Clash of Clans.
4. Tap to Disconnect to remove this game from your account.
5. Done.

Source: Removing Clash of Clans from Google Account

Yes, you can remove your old town hall from your Google account.

1. Open your Android device, of course.
2. Open Google Settings.
3. Open Connected Apps then tap to Clash of Clans.
4. Tap to Disconnect to remove this game from your account.
5. Done.