If a parking is not nose-in, if you set the Pushback preference to "None" in the GSX customization page, when you select a Departure, it will ASK if you want to be Pushback so, if you reply NO there, it will just remove vehicles and cones.
The reason for that question, is that GSX cannot possibly know for sure if the Pushback has been set to None intentionally ( like in that case ) or by mistake, or if that parking position might possibly be used in both configuration ( nose-in or not ), so you always have a chance to get a Pushback, if needed.
Also, there's a global option in the Settings "Always ask for Pushback", which if Enabled will always show the Pushback question, while if it's Disabled ( default is Disabled ), will only make such question for parking spots that has been set to "None" as Pushback preference.