It is not possible to directly rename the db2 instance name, But following steps can be used to move the db to new instance
Take the backup of DB's and provide 755 permissions to backup images. Offline backup is recommended
db2stop command to stop the instance
drop current instance name by using db2idrop command
create new instance by using db2icrt command
once instance is created, switch to the instance id and please start the instance by db2start command
Restore the db to new instance name by using below command incase of auto storage
db2 restore db from ON NEWLOGPATH
If there are user defined tablespaces, Which will need redirect restore
db2 connect to
or Run below command to grant DBADM access to dbroot.
db2 " grant DBADM WITH DATAACCESS on database to user dbroot";