Make sure you are logged in and at the My eSIMs page, follow these steps:
1. Scroll al the way to the bottom of the page
2. Click on 'Archived'
3. Click on the eSIM you wish to unarchive
4. Under 'Actions', click on 'Unarchive eSIM'
4. On the window that pops up click on 'Continue'
That is all!