This code is in vb but it should give you your answer.
pFLayer is your lineLayer as IFeatureLayer
_map is your DotSpatial.Controls.Map
pFLayer is your lineLayer as IFeatureLayer
_map is your DotSpatial.Controls.Map
pFLayer.RemoveSelectedFeatures()
pFLayer.DataSet.UpdateExtent()
pFLayer.DataSet.InitializeVertices()
If pFLayer.LabelLayer IsNot Nothing Then pFLayer.LabelLayer.CreateLabels()
If save Then
pFLayer.DataSet.Save()
pFLayer.DataSet.Close()
End If
pFLayer.AssignFastDrawnStates()
If _map IsNot Nothing Then
_map.Refresh()
_map.ResetBuffer()
End If