To
delete a normal constraint, delete the normal constraint node.
To
delete a normal constraint
Select
the normal constraint node only. (Select the normal constraint’s selection
handle if displayed, or use the Hypergraph to
select the normal constraint node.)
Select
Edit > Delete (default
shortcut: (Linux
and Windows) or (Mac
OS X) key).
(Linux
and Windows) or 
(Mac
OS X) key).