Migrating a database from Oracle ASM to an alternative storage system is essentially the reverse of the migration to Oracle ASM. Modify the steps in "Preparing to Migrate the Database to Oracle ASM Using RMAN" and "Migrating the Database to Oracle ASM Using RMAN" as follows:
If the procedure specifies Oracle Managed Files locations, then alter the procedure to use locations in alternative storage.
If the FORMAT clause of the BACKUP command specifies an Oracle ASM location, then change the backup format to an alternative storage location.
If a file name used in a SQL statement is an Oracle ASM location, then change it to a file name in the alternative storage location.