As you have been allotted the first choice then you can't opt for the upgrade. If UPSEE is providing you the option to upgrade or float then you can click on it or in the next round there is very less possibility that you will get anyother college but you can watch what happens. In general such mistakes are very silly and you must have been more sincere. Although its now very absurd to think of it, just wait and see what happens. As per the official notification there are no conclusive statement provided the UPSEE counselling authority regarding the choice correlated rules.

To know more about the UPSEE counselling visit the link below:

https://engineering.careers360.com/articles/upsee-counselling

I hope this answer helps. All the very best for your future endeavors!