Dear student,

As you have chosen float option, then now you can't change your willingness.
In general, float means - YES UPGRADATION.

In other words if you float your seat then that means you have accepted the seat but you want a higher preference branch in other institutes in further rounds. If you got any higher preference branch in further rounds then you will accept it and your previously alloted seat will get cancelled.

Otherwise if you not get any higher preference seat, then your previously alloted seat will remain with you.
Otherwise there is no chance that you can change your willingness.

Also check out the following link to know more about upsee counseling :-
https://engineering.careers360.com/articles/upsee-counselling