Hide Finder From Dock in Sierra
I found the answer while playing with Path Finder's preferences and finding this option: "Enable Finder's "Remove from Dock" menu option. Upon clicking on it, I got the following message:



To disable SIP, however, you have to enter recovery mode. Here is more information about it on HowToGeek:

https://www.howtogeek.com/230424/how-to-disable-system-integrity-protection-on-a-mac-and-why-you-shouldnt/