Hi gabby,

We do not have the option of changing email address from secondary user account to primary account. However you can cancel your primary email account and sign up with the secondary user account as primary account. You need to manually inform all the contacts regarding change of your email address.

The other option would to create alias account. Please find the steps below for creating an alias account:

1. Sign in to Windows Live Hotmail by using your Windows Live ID.
2. On the upper-right corner of the Hotmail page, click Options, and then click More options.
3. On the Hotmail Options page, under Managing your account, click Account Details (password, aliases ,time zone)
4. Under Other Options, click your email addresses.
5. Click Add an email address.
6. Type a new email address, and then click the Add button
7.  After adding the alias, sign out of Hotmail and sign back in to use the alias account.
8.  You would see your alias account under your Inbox in the left pane.