When you edit a derived template and publish the changes, all pages built on that template are updated accordingly (they "inherit" the changes, providing that inheritance has not been broken). However, if one of your changes is to delete an element that was on the template, then, before you use the yellow work-in-progress icon to submit the change for publication, the following sequence happens:
Click on the gear wheel icon; click on "more"; select "Delete..."
A "Confirm Delete" lightbox is displayed; click on "Yes" in the lower right if you really mean it.
A "Delete Template Element" lightbox is displayed, asking whether you want to:
Delete all instances of this element. Delete the element from the template and delete the inherited copy on all existing pages that derive from the template.
Delete element from template only. Delete the element from the current template, and therefore from all pages made in the future using this template, but leave originally inherited elements intact on pages that have already been made using this template. (See warning, below.)
If you choose the former (which is the default with the current version of CommonSpot), then every instance of that element will be removed, irretrievably. If the element in question was identical everywhere, having been inherited from the template and not modified, then it can be replaced with a single update to the template. If the element in question had been modified differently on various pages, then each of those separate versions would have to be re-created, one at a time. This risk that you or a future pagemaster might accidentally destroy multiple content items is a strong motivation to design your template carefully and to keep it locked-down.
If you choose the latter, then those "orphaned" elements on each page will each have to be individually modified for any future updates, because there is no element in the template for them to inherit changes from; furthermore, the act of revising the element may break inheritance for the layout element containing it.
There are circumstances (involving already-broken inheritance) where even though the "delete from template only" choice is selected, the elements are in fact deleted irretrievably from the derived templates and pages built on the template being revised. It is wise to approach with caution any element deletion from a template. Be sure that you have the resources available to re-construct any content (on that template and any derived template or page built on it) that may be unexpectedly destroyed.
Therefore, we urge you to design your templates with complete elements (which will be kept intact on each page derived from the template) and with phantom "Click here to define the layout" placeholder items, but do not build your templates with any other elements that are phantom "click to define..." or that are intended to be modified on individual pages. In other words, what belongs in the template are the things that will be the same on all pages built on that template. For example, the boilerplate should not be in the template, because its content is page-specific. You can reduce work by copying the boilerplate element from another page and pasting it into your new page, then revise it to show the correct URL and date. You may also choose to create your page by copying a secondary blank page that includes the boilerplate element, ready to be revised.