The More tab contains some advanced tools related to the currently selected layer.  You can access this screen by clicking on a layer on the Layers screen and then clicking on the More tab.

Remove Layer
Click this button to remove the currently selected layer from your map.  If this same layer belongs to other maps on your account then the layer will simply be removed from this map but remain on the other maps.  But if this is the only map that includes this layer then the layer and any attached documents will be permenantly deleted.  Only map managers can delete a layer from a map.  For more about how to share layers across multiple maps see Create New Layer.

Add/Remove Fields
Click this button to modify the list of fields associated with features on this layer.  See Add/Remove Fields for more details.  You must be an authorized editor of this layer to modify the field layout.  

Template Manager
Click here to display the layer template manager screen.

Backup Manager
Click here to display the Backup Manager screen.