Delete
Highlighted elements can be deleted by...
- the icon
under 
- pressing the key [Del]
- Menu Edit / "Delete"
This function is used to delete selected elements from the schematic or the PCB layout, it is a three step procedure:
If any additional tracks that were created by the "autorouter" are selected for deletion, only these tracks will be deleted. If manually routed signals/tracks are selected, only these will be deleted. All selected symbols or packages will diappear after deletion.
In some cases it may be necessary to execute the delete command up to three times (or by pressing the [Del] key), until all selected elements and components disappear. If you delete only signal segment connected to a particular pin, such a pin will be released and therefore made available for connection again (the pin gets an X again). The last 50 changes, including deletions, can be undone with the 
"Undo" function.