I've been banned from the UK for 10 years for not providing full information. Now I am an Australian citizen. Does this ban still exist? Any guidance will be appreciated.
Yes, the ban still applies.
The ban applies to the person, not the citizenship. Even though as an Australian Citizen you do not need a visa to visit the UK, you are still subject to the 10 year ban, and thus can not visit.
It is possible that if you were to attempt to visit the UK using your Australian passport you would be admitted on the grounds that they may not realize you were the same person that was banned, however even this is unlikely as you will still have the same name, date of birth, and place of birth (all of which are on your passport). Even so, this would be illegal, and you would likely be subject to a further ban if you were caught.
You could certainly attempt to apply for a new visa for the UK. Given your new citizenship it is possible they may choose to overturn the ban, although I can't comment on how likely (or not) that would be.