Hi Tracy,
Some customers encounter problems with the ALMService_user when installing TDM. Did you encounter this problem and have to create the user manually or was the user automatically created by TDM when installing, the default behavior? If created manually, then you would be able to delete. I would have to research a way to delete the default one.
Are you receiving this error? Unable to create user account or group 'ALMService_user' on the local machine. Error Code: 2245. The password does not meet the password policy requirements. Check the minimum password length, password complexity and password history requirements.
Since you are no longer using ALM, are you able to uninstall the GT HP ALM Service from Control Panel?