You can link your new account to your learning profile by clicking on your profile icon in the top right corner and selecting settings.
Scroll down on the settings screen until you see 'Account Management' then below linked accounts choose +Add Account.
Once you have added your new email account. Sign into the Microsoft learning platform using your new account details. Go to your profile icon in the top right corner again and select settings. Scroll down to Linked accounts. Then you can remove the old account email address. Any future sign in will use the new email address.