Instance
To delete a block instance, select the block instance, then use the del key on your keyboard.
Deleting the instance does not remove the definition from your project, even if it's the last instance on your canvas.
Any block definitions remain until they are specifically removed, so you can re-use block definitions later and treat them like a library of components.
Definition
To delete a block definition, open the block manager.
Mouse over the block you want to delete, and click the bin icon.
Confirm the deletion:
Cancel - return to block manager
Confirm - delete block definition.
When you delete a block definition, any instances remaining on the map will be converted to a generic point, and may encounter errors. Delete the points to remove the error.
Delete Unused
To quickly purge all unused block definitions, open the command line (tap spacebar).
Search "delete"
Select "Delete unused blocks"
Confirm delete:
All block definitions that do no have instances in the current project will be removed.