My dentist wants to take off my braces but I feel as though my teeth aren’t straight? (Photo)

Hi there, My dentist would like to take my braces off next week and I am still not content with the result I have. I believe my UL1 tooth is not correctly aligned- my dentist has said once my braces come off they can do further refinement but surely this should be something that braces can fix? On my lower brace, he has told me that one of the teeth will not rotate any further and that I can leave it on for longer if I would like- is this true or is he trying to rush this process?