If the component that you are tracing has stopped, you can delete its trace files from the log subdirectory of the IBM® Integration Bus home directory.
If you are tracing an integration server, you can use the -r parameter of the mqsichangetrace command to reset (clear) the trace log (the -r parameter can be specified only if you specify the -e parameter). You might clear the log when you start a new trace, to ensure that all the records on the log are unique to the new trace.
WBRK_BROKER specifies the name of the broker
-u specifies user trace
-e specifies the integration server (in this case the default integration server)
-r clears the trace log
On z/OS®, enter the command F MQP1BRK,ct u=yes, e='default', r=yes