Chart.js Bar Chart: How to remove space between the bars in v2.3?

You need to set barPercentage and categoryPercentage to 1.0 on the x-axis scale. Add this to your options object:

var options = {
    ...
    scales: {
        xAxes: [{
            categoryPercentage: 1.0,
            barPercentage: 1.0
        }]
    }
};

See http://www.chartjs.org/docs/#bar-chart-chart-options