As stated in the title - I created a scratch org and created additional user on it using SFDX. Then after deleting this environment when I try to create user with the same name on another scratch org I keep getting error:
The username "firstname.lastname@example.org" already exists in this or another Salesforce org. Usernames must be unique across all Salesforce orgs.
So, how to delete user (or at least change its name) from a scratch org that I don't have access to anymore?