Pushpith,
The dropdown enablement is exposed via:
C:\Program Files (x86)\CA\SC\CommonReporting4\tomcat\webapps\BOE\WEB-INF\config\default\BIlaunchpad.properties
# You can specify the default Authentication types here. secEnterprise, secLDAP, secWinAD, secSAPR3
authentication.default=secEnterprise
# Choose whether to let the user change the authentication type. If it isn't shown the default authentication type from above will be used
authentication.visible=false
If the authentication.visible = false, then you do not get an option to select a different authentication type other than the default one specified in the first option.
Note: this impacts all users, restart of BI Tomcat is needed for the change to be effective
Hope this helps
_R