NO.
Ducks cannot bite your finger off or bite any part of your body off.
The reason ducks cannot bite your finger off is the ducks do not have teeth and without teeth they cannot bite something off.
A duck can still attack a human though and may cause some bleeding if they pierce your skin with their beak which is possible.
However most ducks will not attack you or try to bite you as long as you're friendly to the duck.
I've been around ducks and most of the ducks are pretty friendly.
Although I remember my younger brother when he was 3 years old and still in diapers he tried to chase after a duck at a park one day and the duck came back and tried to tear his diaper off of him.
That was funny and I wish I had video of that.
I was around 15 at the time and still remember this.
I think my mom has a picture of it somewhere.
He was running around outside at the park on a hot summer day in just his diaper, shirt and shoes.
He hated wearing clothes other than a shirt on summer days and would not even wear shorts.