If you enter an invalid equation that can't be graphed, Graphmatica will automatically prevent the equation from being added to the redraw queue. But sometimes, you may need to trim unwanted equations from the redraw queue (for example, before saving a list of equations).
To delete an equation, first select it, and then choose Delete Graph from the Edit menu. If the equation is currently on screen, its graph will disappear immediately.
See also Clearing the Redraw Queue for how to clear the entire redraw queue at once.
Shortcut: Right-clicking on a curve will bring up a popup menu with Delete Graph in it as well.