You have been auto-demoted from User to Leecher because you have downloaded more than 5GB and your share ratio has dropped below 0.3. To be promoted to User again, you will need to improve your ratio so that it is above 0.3.
To avoid having your account deleted, please read and follow the following:
Your current download amount has been recorded (6.09 GB) and your account will be automatically deleted if you download more than an additional 10GB (i.e. if your download amount exceeds 16.09 GB). You are only entitled to remain a Leecher for 28 days -- if you have not achieved a 0.3 ratio or above within 28 days, your account will be deleted.
As a Leecher, you are still allowed to have 3 active downloads (however, you can seed as many torrents as you like).
If you are finding it difficult to attain a good ratio then there are lots of helpful tips in the UG Wiki, the FAQ, and in the help forums. If you have any questions then please ask in the help forums -- do not PM a member of staff directly.
Also, as a reminder, a donation of $20 USD or more will give you a permanent promotion to the class of VIP where you will be immune to automatic demotion, account pruning, as well as account disabling due to a poor ratio.