The Explode All button will break objects down into their individual segments used to create it. 

Have the design on the screen.

Click the Explode All button.

The object is broken down into its individual segments which can now be edited separately.

For an example, select the desired arc to delete.

The selected arc is deleted.

You can further edit the design and add other elements.

Optionally, click Edit>Explode All.

The entire design is exploded into its individual segments.

Optionally, you can manually explode selected objects with the Explode Circuit button.

This allows you to manually select which objects to explode.