How do I delete iphoto icon from dock in El Capitan op

I have macbook unibody 2010. No photos on it.

Just installed new op El Captian

Still has iPhoto icon with crossed out circle in dock

How do I delete iphoto icon from dock?

I've deleted iPhoto from applications

But crossed out icon still showing in dock

Wanting to sell laptop, but it looks like somethings wrong with iPhoto crossed out but still on dock

I do have the new photo icon on dock.

How do I delete iphoto icon from the dock?

MacBook (13-inch Mid 2010), OX 11 El Capitan operating system