Use the Layer List to manage what layers are displayed on the map. 

Turning Map Layers On and Off

• Select the Map Tools folder 
  and the Layer List tool
  to view the list of available map layers. The Layer List contains groupings of layers available for display on the web map. Expand/Collapse layer groups to view the layers within each grouping.
• Turn on/off layers for display by clicking the eye icon.

• Click the ellipses icon to the right of each layer for additional options.

• Zoom To will zoom the map extent to show all of the features in that layer.
• Transparency allows you to alter the opacity of the selected layer.

• Move up will move the layer above the previous layer in the Layer List. The symbology for the layer moved will be drawn on top of layer(s) below it.
• Move down will move the layer below the previous layer in the Layer List. All symbology for the layer(s) above the layer will be drawn first.
• Disable/Enable pop-up will toggle off and on the pop-ups for this layer so that they do/do not appear when the layer features are clicked.
• View in Attribute Table will open the attribute table for the layer.