export your landcover map

export the results of the random forest classification

step 1: add the image and training data

var image = ee.Image("users/servirmekong/Vietnam/Sent2_2017_Forest001")
var referenceData = ee.FeatureCollection("users/servirmekong/Vietnam/ReferenceDataForestTraining");
var chl = ee.FeatureCollection("users/servirmekong/Vietnam/CHL_Boundary").geometry();

step 2:  select the training data

var referenceData = referenceData.randomColumn("random");
var sample = referenceData.filter(ee.Filter.lt("random",0.8));
var trainingSample = image.sampleRegions(sample,["land_class"],10);

step 3: Train the classifier

var bandNames = image.bandNames();
var classifier = ee.Classifier.randomForest(100,0).train(trainingSample,"land_class",bandNames);

step 4: classify the image

var classification = image.classify(classifier,'Mode');

step 5: Add the image to the map and export the result

Map.addLayer(classification,{min:0,max:4,palette:"blue,purple,darkred,yellow,darkgreen"},"land cover map")

Export.image.toAsset({image:classification,
                    region:chl,
                    maxPixels:1e13,
                    scale:10})

example