There is no direct way to remove this message from the system.
Few options here
1.You can change the message i.e "Invalid update" to the text you want from message table. Please note this would be a global change.
2.Second option is to include additional message on the form. Please refer below link for more info.
http://wiki.servicenow.com/index.php?title=Scripting_Alert,_Info,_and_Error_Messages
