I am trying not to show the labels of x-axis, which in this case are:
7.5, 8.0, 8.5, 9.0 and so on.

This is what I have tried so far:

<div id=chartdiv></div>



var chart = AmCharts.makeChart(chartdiv, {

theme: light,

type: serial,

dataProvider: [{

    name: 3s,

    startTime: 8,

    endTime: 11,

    color: #FF0F00

}],

valueAxes: [{

    axisAlpha: 0,

    gridAlpha: 0.1

}],

startDuration: 1,

graphs: [{

    balloonText: <b>[[category]]</b><br>starts at [[startTime]]<br>ends at [[endTime]],

    colorField: color,

    fillAlphas: 0.8,

    lineAlpha: 0,

    openField: startTime,

    type: column,

    valueField: endTime

}],

rotate: true,

columnWidth: 1,

categoryField: name,  

});

JSFiddle Demo