Hi, and welcome to Justanswer. My name is ***** ***** i will be assisting you today.
First, do you have access to both accounts?
Sign out of both your primary and secondary account, then go to System Preferences>iCloud and sign in with the secondary account ID.
This makes the secondary, your primary.
Before you delete the primary, ensure you back up all data on the primary.
This is for deletion:
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(also, if you are on a windows pc, the 'system preferences' is called Control Panel)