Depends on the system. In Norway, parties fields lists, but you can strike out the names of candidates you don't like, or add additional names.

The list you vote for determined how many seats that list (party) get in each region, but striking names or adding names of people on other lists alters the order in which seats will get allocated to the people on the lists.

It is not very often used, but when particularly controversial candidates are fielded it sometimes does affect who gets in.