Can't login to account after changing alias

Well you can't change the login only the alias nowadayd

Login to the website http://www.account.live.com with the Microsoft Account that you created with windows phone. Where it says "(primary alias)" there is a link below that says "add or change aliases".
The next page will allow you to add or create a new email alias. Once you have added the new e-mail alias you can remove the previous email. After that email is gone it will be free of the account and you can then add that as the primary alias on your preferred
gamertag. Simply login on the Microsoft Account that you want to use that email on and follow the same procedure as above.

Hello, DB-510

Welcome to the Microsoft Community.

I understand that you are having problems trying to change your Xbox and Microsoft account association.

I will address your issue in as much detail as possible to explain the Microsoft account and Xbox account association.

Allow me to clarify that if you want to change your Xbox account login, you can change the login email used for your Xbox account by adding an alias to it. For example, if you add an email alias to the Microsoft email associated with your Xbox account and set it as the primary alias, this alias can be used as your new Xbox login email, but existing Hotmail, Live, Outlook.com, and MSN addresses can't be added as aliases, and you can't add an alias that is already associated with another Microsoft account.

Since your primary email is linked to another Xbox account that can't be deleted, then this operation is basically impossible to accomplish, and you can refer to the discussion in this thread regarding your desire to remove the old Xbox profile from your account and put the correct Xbox profile into your primary email:

How to transfer an Xbox profile and all of its contents to another - Microsoft Community

Best Regards.

| Microsoft Community Support Specialist

I have seen this and I was able to login into the account in the first day but after about 30 hours I couldn't login. As I said, nothing showed up later when the main alias was deleted. I didn't set my primary alias and I was able to deleted the main alias.

Try changing it online instead. Go to
http://www.account.live.com Login with your current Microsoft Account e-mail address and as soon as your login, under overview you will see primary account alias, and that will show your current e-mail. Under that you will see the option to add or change
primary alias... so just fill in required info and that should do it for you.