prompt How to drop a file in the ASM diskgroup ? 
prompt ALTER DISKGROUP dgname ADD DIRECTORY '+U02/ORCL/X'
prompt ALTER DISKGROUP dgname drop file '<file name>';
prompt ALTER DISKGROUP dgname DROP DIRECTORY '+U02/ORCL/X'
prompt ALTER DISKGROUP dgname DROP ALIAS '+U02/ORCL/X/1_9_589626613.dbf'
prompt ALTER DISKGROUP dgname RENAME ALIAS '+U02/ORCL/X/1_7_589626613.dbf' TO '+U02/ORCL/1_7_589626613.dbf'