Open a document with a custom shape.
Click the custom shape to select it, then choose Format > Shapes and Lines > Save to My Shapes (from the Format menu at the top of your screen).
The shape is saved in the My Shapes category of the shapes library, which appears only when you have custom shapes. Shapes appear in the library in the order you create them; you can’t change this order.
Type a name for the shape in the field that appears below it, or click the name to change it.
To delete a custom shape, Draw a shape in Pages on Mac