If you see the error message that a user account with the specified email address already exists when you create a user account or change an email address, then you cannot create the user account.
If you do not find a user account for the email address in the employee overview, then the employee previously created their own user account. This user account is completely separate from your user group, so you do not see it.
So to create a new user account with the desired email address, you need to delete the existing user account first. The owner of the user account proceeds as follows:
1. The user goes to timebutler.de and signs in (if not signed in automatically). If the user no longer knows the password, they can click the “Forgot password” link on the sign-in page.
2. Now the user clicks “Settings > Your user account” in the lower left.
3. On the following page, the user clicks the “Delete user account” button and follows the instructions on the page to delete the user account. Note, however: deleting the user account permanently deletes the account and all associated data.
After the user deletes the account, you can sign in to Timebutler and create a new user account with the desired email address.