All of the graphical elements in Gnumeric can be deleted using the context menu. Deleting a graphical element will never alter the data contents of the cells in the workbooks.
Deleting a graphical element requires using the context menu. First the mouse pointer must be placed over the graphical element. Next, the context menu must be invoked by clicking with one of the secondary mouse buttons. Finally, the Delete menu item must be selected by placing the mouse pointer over this menu item and clicking with the primary mouse button. When this menu item is selected, the graphical element will disappear from the worksheet and will not be saved as part of the spreadsheet file the next time the file is saved.