Sometimes we have to remove a configuration from the Grid Infra, this is done again fairly simple, just BE SURE YOU WANT TO DO IT :)
Basically to command to remove database configuration is the following:
[oracle@Naos dbs]$ . oraenv
ORACLE_SID = [rcat] ? +ASM
The Oracle base has been changed from /u01/app/oracle to /u01/app/12.2.0
[oracle@Naos dbs]$ crsctl stat res -t
--------------------------------------------------------------------------------
Name Target State Server State details
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.BANKINGDATA.dg
ONLINE ONLINE naos STABLE
ora.BANKINGFRA.dg
ONLINE ONLINE naos STABLE
ora.LISTENER.lsnr
ONLINE ONLINE naos STABLE
ora.RCATDATA.dg
ONLINE ONLINE naos STABLE
ora.RCATFRA.dg
ONLINE ONLINE naos STABLE
ora.asm
ONLINE ONLINE naos Started,STABLE
ora.ons
OFFLINE OFFLINE naos STABLE
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.cssd
1 ONLINE ONLINE naos STABLE
ora.diskmon
1 OFFLINE OFFLINE STABLE
ora.evmd
1 ONLINE ONLINE naos STABLE
ora.rcat.db
1 OFFLINE OFFLINE STABLE
--------------------------------------------------------------------------------
[oracle@Naos dbs]$ srvctl remove database -db rcat
Remove the database rcat? (y/[n]) y
[oracle@Naos dbs]$
[oracle@Naos dbs]$ crsctl stat res -t
--------------------------------------------------------------------------------
Name Target State Server State details
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.BANKINGDATA.dg
ONLINE ONLINE naos STABLE
ora.BANKINGFRA.dg
ONLINE ONLINE naos STABLE
ora.LISTENER.lsnr
ONLINE ONLINE naos STABLE
ora.RCATDATA.dg
ONLINE ONLINE naos STABLE
ora.RCATFRA.dg
ONLINE ONLINE naos STABLE
ora.asm
ONLINE ONLINE naos Started,STABLE
ora.ons
OFFLINE OFFLINE naos STABLE
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.cssd
1 ONLINE ONLINE naos STABLE
ora.diskmon
1 OFFLINE OFFLINE STABLE
ora.evmd
1 ONLINE ONLINE naos STABLE
--------------------------------------------------------------------------------
[oracle@Naos dbs]$