Merging requires you to use the Contact Us form at the bottom of the page to get staff to do it. Moderators cannot merge your accounts. See the note in the help center about merging accounts: https://askubuntu.com/help/merging-accounts
I accidentally created two accounts; how do I merge them?
If you have two accounts that you would like to join together, please
sign into either account, visit the Contact form, select "Account
Issue", and then select "I need to merge user profiles". After
you contact us, the Stack Exchange Team will reach out to verify that
you own both accounts. If we can confirm your ownership, we will
initiate a merge.
If you can't remember how to log in, go here and enter the email
address you used to create the account you are trying to sign into.