Try for just one day to go with out it. Get up and get ready for your day without dressing in something someone else will like. Wear something you want to wear and something comfortable. With staying in the reasonable allowances for your work or whatever your plans are. IE: If you work in an office and you are supposed to dress business casual. Dress business casual. But if there is a blazer you have been wanting to try with a certain shirt, but not sure of the colours together. Just wear it. You will know if YOU like it by the end of the day.
Go through your day not judging anyone and pay to no mind of people who you feel might be judging you. It doesn't matter.
I read a book a while ago about ego. I have tried this exercise and it is very difficult, BUT very liberating.