By default, if code resides outside an <!--Editable Region--> those portions of the child page spawned from DWTemplate are NOT EDITABLE. The only way you can edit code outside editable regions is to open the original DWTemplate.
Now if your question is "how do I convert an editable region into a non-editable region?"
The answer is open your DWTemplate and re-edit it by adding new editable regions and/or taking away old ones. I hope this makes sense.
More on DWTemplates -