Thank you Chris R. Spartz , I check the method server log,it shows like " ptcServiceName XXX dc=XXX :18004 dc=XXXX o=XXX" I remember I have seen the alike string in the Info Engine. So, I enter into the Info Engine and check the "Adapter" the port is 18022 and 18023(because we start two method server so there are two adapters here ) and I delete the two entries of Adapter and recreate a adapter whose port is 18004 , I clean the <WH_homw>/tasks/codebase directory (rm -rf <WH_homw>/tasks/codebase) and I restart the Windchill
and I can delete the disconnected principals in the web page .
Thank you very much ~