For multiple node RAC servers, the diskgroup must be dismounted from all the other nodes, except the one that we are issuing the command.
SQL> DROP DISKGROUP DATA INCLUDING CONTENTS;
DROP DISKGROUP DATA INCLUDING CONTENTS
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15073: diskgroup DATA is mounted by another ASM instance
On Node2, Node3, ….etc
SQL> ALTER DISKGROUP DATA DISMOUNT;
Then on Node1
SQL> DROP DISKGROUP OCRVOTING INCLUDING CONTENTS; Diskgroup dropped.