Mae wanted to destroy the circle at the end of it and take down its top leaders then how in the final scene are there still drones flying around her monitoring her every move?
I think you are misunderstanding.
Mae wasn't taking down the Circle, she was just making the point that transparency should apply to everyone.
She has no issue with being transparent 24 / 7 / 365 but she feels that transparency should be both total and universal.
As she is talking, she tells them how Ty has found all their accounts, even the accounts that their wives were unaware of, and is exposing them in an attempt to become fully transparent because no one should be exempt.
If so how is the Circle still a thing?
The Circle is still a thing because it was never destroyed. She TeeChange cameras are everywhere and there is now (or proposed) universal voting through Circle accounts.
As such, the Circle is now (or will be) a quasi-governemental organisation. Essentially, it's become an extension of the government (although it has no control of the populace) but due the transparency it's a benign organisation.