I want to replace my primary apple id with my rescue apple id

You will first need to remove it as your rescue email address (from here) :

1. Navigate to appleid.apple.com using your web browser.
2. Click "Manage your account"
3. When prompted, sign in using your Apple ID and password.
4. Click Password & Security
5. You'll be asked to answer 2 of your 3 security questions before you can make any modifications. If you are unable to remember your answers, you can choose to send an email to your rescue email to reset your security questions.
6. After you've validated your identity by correctly answering your security questions, click Editto the right of your rescue email address.
7. Once you've finished editing your rescue email address, click the Savebutton directly below the email field.

You should then be able to use it as your main email address (I'm not sure whether you will need to logout of that site and then log back in to be able to do it)

What options do you see on the right-hand side of that screen - I get :