To remove an issue from the current structure, select this issue and press Delete button on the keyboard or click Delete button on the toolbar. The issue is removed with all its children issues.

The issue will be removed from the structure and placed into the Removed Issues secondary panel. You can access it by clicking the Trash icon in the top right corner. To move deleted issues back into the structure, simply select them in the Removed Issues panel and use drag-and-drop or cut/paste to place the issues in the structure.

Once you leave the current page, the Removed Issues panel is emptied.

Removing an issue from a structure does not delete the issue itself. It just removes it from the current structure.