@Viet Tran
There actually is a way OOTB to re-assign a work order to another resource. I tested this thoroughly this morning. In the Work Orders graphite application, select a work order, click on the Plans menu on the left, and in Work Order resources, it shows the responsibility (which in this case is the supervisor and the owner I have set up on the work order in Wotrack), and there is an 'edit resources" selection on the right. (see pic). In the edit resources, the owner and supervisor are shown, and these can be changed. As well, scrolling down in the page, the "labor or crew assignment" can also be changed. The trick here is that the current Labor line has to be deleted (click it an a trash can appears), and then click the SAVE button. If you go back in the Work Orders bread crumb, and press F5 to refresh, the assignment will show 0. Then you can go in and edit the resource again, scroll down, and then add a Labor line. Do another SAVE and refresh, and the work order will show the new assignment. So, the lines have to be deleted, saved, refreshed, go back in and assign, and save and refresh again, but it will update the work order with the new assignment (the Scheduled Start time on the work order is updated and displays the current time on your computer). And the Workorder Assignment native application will reflect the assignment as well. Sweet.