>> or with a body part that has been removed
If I remember the order correctly:
One of the first attacks on finger print readers was to blow on them, making them read the remains on the previous fingerprint used. That was fixed by adding a temperature sensor to the reader, so to attack it you had to use a plastic bag with water at around human temperature. The easy fix was to also check for a pulse while reading the fingerprint, this also make it impossible to use a removed body part.
I have not kept up with the progress in the last years, so not sure how good creating a fake fingerprint that you put on top of your own prints work, like they do in movies. Finding and reproducing a print is not that hard.
As others have written, fingerprint are usernames. It is not secret and you can not change it