OBIEE 11g Logs Periodic Purging

I want information about how the logs are maintained in OBIEE11g.

With OBIEE 10g, most developers knew where to look for the log files which hopefully provided the information necessary to solve a problem.  What about with 11g?  Where are they and how can they be accessed?
You can check the different log files in the Oracle Business Intelligence (OBIEE).  The right way to check them is using the Enterprise Manager (EM) Console page.
EM Console. Login to the URL http://server.domain:7001/em and navigate to:
Farm_bifoundation_domain-> Business Intelligence-> coreapplications-> Dagnostics-> Log Messages
You will find the available files:

• Presentation Services Log
• Server Log
• Scheduler Log
• JavaHost Log
• Cluster Controller Log
• Action Services Log
• Security Services Log
• Administrator Services Log

However, you can also review them directly on the hard disk.
The log files for OBIEE components are under <OBIEE_HOME>/instances/instance1/diagnostics/logs.  Specific log files and their location is defined in the following table:

Log	Location
Installation log	<OBIEE_HOME>/logs
nqquery log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIServerComponent/coreapplication_obis1
nqserver log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIServerComponent/coreapplication_obis1
servername_NQSAdminTool log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIServerComponent/coreapplication_obis1
servername_NQSUDMLExec log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIServerComponent/coreapplication_obis1
servername_obieerpdmigrateutil log (Migration log)	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIServerComponent/coreapplication_obis1
sawlog0 log (presentation)	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIPresentationServicesComponent/coreapplication_obips1
jh log (Java Host)	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIJavaHostComponent\coreapplication_obijh
webcatupgrade log (Web Catalog Upgrade)	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIPresentationServicesComponent/coreapplication_obips1
nqscheduler log (Agents)	<OBIEE_HOME>/instances/instance1/diagnostics/logsOracleBISchedulerComponent/coreapplication_obisch1
nqcluster log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIClusterControllerComponent\coreapplication_obiccs1
ODBC log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OracleBIODBCComponent/coreapplication_obips1
opmn log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OPMN/opmn
debug log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OPMN/opmn
logquery log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OPMN/opmn
service log	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OPMN/opmn
opmn out	<OBIEE_HOME>/instances/instance1/diagnostics/logs/OPMN/opmn
Upgrade Assistant log	<OBIEE_HOME>Oracle_BI1/upgrade/logs

What is the periodic frequency of the logs to be deleted. ?
As aegs mentioned.

Is there any probelm if I  delete log file directly in my server.?
Nope,But it is not a best practice