Last year I entered info on fidelity investments...I no longer have that and it is prudential and it keeps asking me to enter info from fidelity?

Delete that form (Fidelity) and click on Add Another sale.  Enter the new Prudential form after deleting the Fidelity form that transferred in from last year's return.  

If you are not in that section, search for 1099-b and click on the Jump to 1099-b link.   You will be taken to your Investment Summary.   From here, you can delete Fidelity and add Prudential.  Look for the trash can icon or Delete button to delete forms.