Code:
Sub DeleteRowsKEYWORD()
Dim TargetText As String
Dim oRow As Row
If Selection.Information(wdWithInTable) = False Then Exit Sub
TargetText = "KEYWORD"
For Each oRow In Selection.Tables(1).Rows
If InStr(oRow.Cells(4).Range.Text, TargetText) = 0 Then oRow.Delete
Next oRow
End Sub