There are several methods to delete the disk group from an ASM. It is possible to do this operation with “Enterprise Manager”, asmca and sqlplus. Here we will describe how to do with sqlplus.
First of all, on systems such as rac, you have to dismount the disk group to be deleted, except for the instance you are going to process. For this process, you must load the ASM profile and then connect with sqlplus to use the following command.
SQL> alter diskgroup <diskgrup_name> dismount;
Then you must connect to the instance where the disk group will be deleted and set SID, HOME. If you are sure that the group to be deleted in this instance is in the mount state, you can delete the diskgroup with the following command. The disks in the diskgroup will also be deleted .;
SQL> drop diskgroup <diskgrup_name> including contents;