The Explode button will break up an object into the individual segments that make up the object. 

For example, a rectangle will be broken down into four individual lines which can then be edited separately. 

Click on the desired object(s).

Click the Explode button. 

The selected object will be broken down into the individual segments that make up the object. In this case, it consists of several curves. 

The individual segments can now be edited. Here, one of the curves has been deleted.

Edit the design as desired.

If you need to break an object in a specific place and Explode Circuit isn't sufficient, see "Breaking a Design in a Specific Spot" in the Break topic.

Optionally, click Edit>Explode All.

The entire design is exploded into its individual segments.

Optionally, use the Explode All button.

The objects are exploded into their individual segments used to create it.