Unable to delete a net use device

I am using the NET USE lptn: \\servername\printername /persistent:yes to define remote network printers while connected via Terminal Services. I am having problems reassigning one of the LPT ports to another network printer. When I try to delete the port, (Net Use LPT2: \DELETE) I get the message that the device is in use. I have successfully reassigned that printer on two other PCs. Can anyone advise me as to either releasing the device or point me in the direction of the complete ins and outs of the NET USE command? I have already tried deleting all printers in the printer folder as well and powering off/on the PC and the printer and its server. Thanks.