SQL> sqlplus/nolog
SQL> connect sys/sys as sysdba
SQL> shutdown
SQL> start up
.........
SQL> alter database datafile 'D:SDE.dbf ' offline drop;
SQL> alter database open;
SQL> connect sys/sys as sysdba
SQL> shutdown
SQL> start up
.........
SQL> alter database datafile 'D:SDE.dbf ' offline drop;
SQL> alter database open;