VBA for deleting rows not based on criteria

Try the following

Sub Del_Unwanted()
Dim row_index As Long

Application.ScreenUpdating = False
' Go through each row that has data in G (in reverse order so that the deletion of rows doesn't effect row numbering of rows we haven't worked on yet)
For row_index = Cells(Rows.Count, "G").End(xlUp).row To 1 Step -1
    Select Case Cells(row_index, "G")
        Case "BURHILL", "CSA", "COSC", "DEBE"
        Case Else ' If it's not one of the wanted ones, delete the entire row
            Rows(row_index).EntireRow.Delete
    End Select
Next
Application.ScreenUpdating = True
End Sub