Unable to set cluster_database to false

Hello,

I want to drop a 2 instances RAC database, so when I execute request alter system set cluster_database=FALSE scope=spfile; before dropping database, the cluster_database value is not modified.

Here's my process :

SQL> alter system set cluster_database=FALSE scope=spfile;

System altered.

SQL> shutdown abort

ORACLE instance shut down.

SQL> startup mount exclusive restrict

ORACLE instance started.

Total System Global Area 2.0110E+10 bytes

Fixed Size                  2261888 bytes

Variable Size            3623881856 bytes

Database Buffers         1.6442E+10 bytes

Redo Buffers               41762816 bytes

Database mounted.

SQL> select logins,parallel from v$instance;

LOGINS     PAR

---------- ---

RESTRICTED YES

SQL> set head off

SQL> select name,type,value from v$parameter where name like '%cluster%';