How about answering the original question first? Since it is not explicitly forbidden by the Constitution, can the states expel one state from the Union against its will?
Although your question is more than just a little vague, under certain conditions, the answer is quite obviously 'yes'. (In fact, you may be able to find an analogous example or two in American history! ;^)
Your turn, my friend:
1) Was the federal government delegated any authority over the departure of a member State from the federal union? (Feel free to cite any constitutional clause that supports your answer, if you can.)
2) If no such authority was clearly delegated to the federal government, would it not remain with each of the States - in other words, would not the people of each State retain authority over its own departure? (Again, please feel free to cite any constitutional clause that supports your conclusion. ;^)