All in need is just system messages with time after "#".
How can I trim the result to remove everything else.
The data that you are Serial.write()ing is stored in a buffer - Ethernet::buffer.
Use strtok() to get a pointer to the string up to the first # (hint - the delimiter argument will be "#"). Then, call strtok() again, with a different delimiter string ("\0"), to get the rest of the data (the "DEVOK, 16:28:13 #STSET, 16:28:13 #DASET, 16:28:13" part).
Copy that data to another buffer, and you can use strtok() again on that buffer to get just the parts you want.