Please provide a Migration in the builder or call fallbackToDestructiveMigration in the builder in which case Room will re-create all of the tables

add ".fallbackToDestructiveMigration()" before build(),

If you don’t want to provide migrations and you specifically want your database to be cleared when you upgrade the version, call fallbackToDestructiveMigration in the database builder

database = Room.databaseBuilder(context.getApplicationContext(),
                    UsersDatabase.class, "Sample.db")
            .fallbackToDestructiveMigration()
            .build();

I ran your app from GitHub and made a sample migration from ver 1 to ver 2. It turns our there's a mistake in SQL query. It should be:

static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE users "
        +"ADD COLUMN address TEXT");

    }
};

String > TEXT

It's also preferable to make Room's database instance a singleton, and use it only in Repo/CacheManager class. Please check the gist for a complete code changes - https://gist.github.com/lomza/0f311a1b1e9c896bc58dff925d65eab2