I created a simple process diagram which includes a user task. I wrote the properties fro user task which are candidate groups and other properties too. As per my requirement i wanted to add assignee directly instead of candidate groups, but i can not delete it. IF removed that entry and saved the process, then also it comes again. So finally i had to create a new process diagram.
I gave a try for candidate users, whether the same bug happening for it too, and i was right.
windows XP2, eclipse juno as IDE, java 1.6