Lost Yahoo emails (inbox) during Outlook transfer – Please Help!

Hey, I went to sync my Yahoo email in my outlook and think I forgot to click “leave a copy on server” in advanced settings beforehand.

Now all my emails from years back are missing from my yahoo webmail and sit in my outlook. The whole purpose was to have two spots where all of my emails sit and not just one.

Is there a way to reverse this action and transfer my emails back to Yahoo webmail so i can access them all on there as well?

Currently: Old emails transferred from yahoo to outlook and no longer on yahoo

Need: Old emails back on yahoo webmail and then I will re-do transfer so copies of emails sit on both yahoo webmail and outlook

Please help