The database prefix option has been disabled.

If you have disabled the option :"The database prefix option has been 
disabled". It cannot be enabled through the WHM and should not be 
re-enabled if any databases or database users have been created 
with database prefixing disabled." from WHM and want's to 
re-enabled it but does not find any option as to how to 
re-enable that option don't panic.
Follow the below steps to re-enable that option :
1> Login to Server via SSH as a root user
2> open this file : /var/cpanel/cpanel.config in you favorite editor
[email protected][#] vi /var/cpanel/cpanel.config
and then search for the line : database_prefix=0
and replace it with database_prefix=1
save and quit.
restart the cpanel service
[email protected][#] /etc/init.d/cpanel restart

That’s all you are done.