Sometimes the JCo trace logs are generated even after removing JCo tracing properties in the adapter .tra file. This article explains the key points which need to be taken into consideration in such cases.
 

Check the .tra file to confirm whether the JCo tracing properties has been disabled. Once you find that the properties are disabled then go ahead and restart the adapter to see if it resolves the issue.

# Set the JCo trace
#java.property.jco.trace_level 0
#java.property.jco.trace_path D:\temp\
#Set the trace at JCo middleware layer
#java.property.jrfc.trace 0

Note: The jco_rfcXXXXX_XXXXX.XXX.trc trace files generated in <Adapter_Home>/bin folder are actually the JRFC trace rather than the ordinary JCo trace.

After completing the first step if you are still seeing the issue then check if RFC trace on the RFC Destination has been enabled. You can check with TCODE SM59 in SAPGUI if the RFCDestination has enabled the RFC trace. If RFC trace is enabled in the RFC Destination then regardless of setting the java.property.jrfc.trace to 0 the JRFC trace will still be generated. Make sure that the RFC trace is disabled.

If the issue still persists then we will have to check the adapter configuration in the project. Go to the project (R3Connections > Clients > ExampleConfigurationInboundConnectionClient0 > Advanced) and check if the RFC trace value is set to 0. In case it is set to 1 the JRFC trace will still get generated. Make sure it is set as 0. Once done restart the adapter.