<span>The following is NOT for the Mac Novice:
I found this app to be a bit flakey in Sierra & feel that $10 is a bit much for just setting one parameter in a plist file, so I did some investigation and this is what I found out:
First go to this website and read it to get the idea of what you are trying to do:
The technique is correct but adding the element is a be sketchy and does not reflect the current structure of the MOS.
Then copy "LSUIElement "and place into a text file, sticky, clipping or anything that will preserve it for later use that you can copy to the clipboard from.
Now install Prefs Editor, NOT PrefEdit from MacUpdate (Its Free): https://www.macupdate.com/app/mac/49955/prefs-editor
Quit the app you wish to modify if it is running.
If the app is still in the dock, after quitting, remove it from the dock so it will not remain there.
Follow the instructions from the "CultofMac website to open the info.plist file in the desired app but before you do this, do a "Get Info" on the "Contents folder to be sure you have "write" privileges. If not , add your user name to the list and apply it to enclosed folders. If you don't understand the procedure at this point, you probably should not be trying this, at least until you learn how to do this.
Now open the "info.plist" as the article states but use Prefs Editor instead of TextEdit.
Create a new key with Prefs Editor after unlocking the file in Prefs Editor.
Paste in LSUIElement in the element field and set the field type to "Binary". The flag will default to "False"
Click on "False to set it to "True"
Close Prefs Edit saving the file.
Close the Contents window. Your done.
Relaunch the app - No longer in the Dock.
To reverse the process, do the same thing again except just click on the "True" flag to set it to false.
Repeat the process for any other apps you do not want to show up in the dock.