Select Remove Unfold in the Fold menu to unfold a section previously folded with Fold|Fold, and delete the folding point in the process. The Remove Fold command is enabled only when you’ve placed the text cursor on the first (still visible) line of a folded section.
If you’ve made a selection, then all folding points inside the selection are removed.
Use Fold|Unfold to unfold a section without deleting the folding point.
If the current file type uses automatic folding points, then automatically added folding points that you removed may automatically reappear when you edit the file.