Goodness, that is a difficult task!
Ummmm, change saddle, get rid of the suspension seat post. Change fork for a non-suspension fork. Change tyres to slicks.
I think it would cost you more than it's worth to make it sleeker. It will never be gazelle-like, either, just less cowish.
Where are you located, and how tall are you?
Welcome to BF, and feel free to PM me with any questions
!
East Hill