If you want to retake a course, you can Reset Course Progress, which erases all of your previous progress in that course as well as any saved codes.
The XP earned from a previously finished course will not be deducted from your overall XP.
Note: Individual courses must be updated.
Non-course XP (practise, projects, mobile-specific tasks, and so on) will also not be reset.
If you can't find a second account, send an email to support@datacamp.com with the entire name mentioned on the account, as well as the payment details for your subscription
Note: DataCamp does not presently allow you to merge accounts or transfer XP, although you may trade emails across accounts.