Review this information to identify all instances associated with the Oracle home you want to remove.
To identify all instances associated with the Oracle home you want to remove, enter the following command, where dbname is the name of the database:
$ srvctl status database -d dbname
Alternately, you can check for registered instances by viewing the oratab file:
AIX, HP-UX, or Linux:
$ more /etc/oratab
Oracle Solaris:
$ more /var/opt/oracle/oratab
The output of this command contains entries similar to the following:
+ASM1:/u01/app/12.2.0/grid:N CUST:/u01/app/oracle/product/12.2.0/dbhome_1:N
These entries show that the +ASM Oracle Automatic Storage Management instance in the Oracle Grid Infrastructure for a cluster home (/u01/app/12.2.0/grid) and the CUST Oracle database instance are associated with the Oracle home directory /u01/app/oracle/product/12.2.0/dbhome_1.