Click Lock & Edit to start a new configuration session.
Select the Diagnostics->Diagnostic Modules node in the left pane of the console.
disable or stop or delete the respective module and carry out a restart.
Also please check if any of the options are enabled under console - data source - configuration - diagnostics
Else
1. Shut down WebLogic Server.
2. Clear the /data/store/diagnostics directories
3. Apply the below 3 parameters at JAVA_OPTIONS of your setdomainenv file
-D_Offline_FileDataArchive=true
To control diagnostics data collected from the server instance and the applications running on them. If true, WLDF archives the data collected (default: false).
-Dcom.bea.wlw.netui.disableInstrumentation=true
To control Workshop page flow event reporting . Set to false by default in Workshop 10.1 and earlier). Set to true by default (in Workshop 10.2 and later).
-Dweblogic.connector.ConnectionPoolProfilingEnabled=false
JDBC Connection Pool profiling data (default: false).
4. Restart WebLogic Server.
Else
Take a backup of config.xml and delete the lines from and to
restart
Else
You can adopt a retirement policy by rotating the .dat file
console - diagnostics - archives - select the respective server - create NEW 'Data Retirement Policies' followed by a restart.