No, but the power to admit states and approve changes in their status once they've been allowed to join are powers reserved to Congress. Implied in that it the power to approve leaving as well.
***Implied in that it the power to approve leaving as well.***
No it isn’t. You don’t need permission to leave a group you voluntarily joined even if it took approval of that group to get in. I can quit my job any time I please even though my employer had to “admit” me. Unless there is some provision in the contract that says I owe X amount of days or must provide X days of notice. And there isn’t in the Constitution.
The fact remains that secession is not denied to the states and is thus protected by the 10th Amendment.