SQL Server/T-SQL Tutorial/System Functions/sp unbindefault

sp_unbindefault removes the connection between the default and the data type of the corresponding column

The syntax of this statement is
      CREATE DEFAULT default_name
        AS expression
sp_bindefault is used to bind the defined default value to specific columns.
11>
12> CREATE DEFAULT zip_default AS 94710
13> GO
1>
2> CREATE TYPE zip
3>   FROM CHAR(5) NOT NULL
4> GO
1>
2>
3> sp_bindefault "zip_default", "zip"
4>
5> 
6>
7> sp_unbindefault "zip_default", "zip"
8>
9> drop DEFAULT zip_default;
10>
11> drop type zip;
12> GO