To chop off the unwanted parts of a design in My Editor, open it and left-click on the element you want to get rid of. The selected element will be marked with a blue outline.
Now, press Delete.
Keep doing this until you get rid of all the unwanted elements.
If you want to delete several objects at once, left-click somewhere in the area where are no objects and drag and let go. Several objects will be selected. Again, press Del.
When finishing, select File > Save as and store your design on your computer.