Removes the "section" named CpName from documents
procedure DeleteSection(CpName: String);
"Section" is a part of document. The first item of "section" is the item having checkpoint with non empty name. This name is also a name of "section". If there is no another checkpoint with non empty name below, the last item in the document is also the last item of "section". Otherwise, item with that "checkpoint" starts a new section, and does not belong to the current section.
Method type: viewer-style.
Be careful: this method can produce invalid document.