The following macro deletes all user-defined Linked Styles in a document. It's not clear what more you might want to do.
Code:
Sub CleanStyles()
Dim oSty As Style
With ActiveDocument
On Error Resume Next
For Each oSty In .Styles
If oSty.Linked = True Then
.Styles.Add Name:="TmpSty"
oSty.LinkStyle = "TmpSty"
.Styles("TmpSty").Delete
End If
If oSty.BuiltIn = False Then oSty.Delete
Next
End With
End Sub