Hi! Atlassian accounts can not currently be combined, what is the information you don't want to lose?
If you were referring to Bitbucket accounts (since you submitted this question to the Bitbucket product), you can transfer the ownership of the repository from one account to the other, and then remove the Bitbucket account that you don't want to keep.
Let us know if you have any questions!
Adding more information to what Ana was referring to, after this action you can also add an email alias.
In order to do you can check the link below: