MapBox clear all current markers

You saw this? https://www.mapbox.com/mapbox-gl-js/api/#marker#remove

Instead of map.remove maybe try marker.remove:

var marker = new mapboxgl.Marker().addTo(map);
marker.remove();

If you added the markers like this (to be able to add styling and custom images as markers), then you can simply remove the class (I did it through Jquery though).

Adding markers that are in a GeoJson:

GeoJson.features.forEach(function(marker) {
var el = document.createElement('div');
el.className = 'marker';
new mapboxgl.Marker(el).setLngLat(marker.geometry.coordinates).addTo(map);
});

Removing markers:

$( ".marker" ).remove();

If you added multiple markers, and you want to clear all them on your map, you have to loop overs all markers, and delete them one by one, you will have something like this :

if (currentMarkers!==null) {
    for (var i = currentMarkers.length - 1; i >= 0; i--) {
      currentMarkers[i].remove();
    }
}

Consider thar var currentMarkers contains all markers, you can do this with sometning like :

oneMarker= new mapboxgl.Marker(currentMarkerDiv)
    .setLngLat(marker.geometry.coordinates)
    .addTo(mapboxMap);
    currentMarkers.push(oneMarker);

Where var currentMarkers is a global variable :

var currentMarkers=[];

Full example :

// markers saved here
var currentMarkers=[];

// tmp marker
var oneMarker= new mapboxgl.Marker(currentMarkerDiv)
    .setLngLat(marker.geometry.coordinates)
    .addTo(mapboxMap);

// save tmp marker into currentMarkers
currentMarkers.push(oneMarker);


// remove markers 
if (currentMarkers!==null) {
    for (var i = currentMarkers.length - 1; i >= 0; i--) {
      currentMarkers[i].remove();
    }
}