So then could 49 states decide to disassociate themselves from the 50th and kick it out of the Union?49 States could elect to leave the 1787 Constitutional Union and form their own Union if they wished, sure. Each individual State has the right to leave the Union any time it wants, for any reason or no reason, whatsoever; and independent, Sovereign States can form any compact of association they choose.
"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness. That to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed. That whenever any form of government becomes destructive to these ends, it is the right of the people to alter or to abolish it, and to institute new government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their safety and happiness."