You need to set the x-axis type to data and then specify a format for it. In your chart settings, go to advanced tab, set mode to advanced and then in layout options box you can configure the layout with available options
{
"xaxis": {
"type": "date",
"tickformat": "%H:%M"
}
}
For details please see plotly reference at https://plotly.com/javascript/reference/layout/xaxis/