[2020] if the city was demolished

I would say that all players need to make themselves familiar with the Game Rules as Game Sharing is strictly forbidden @Tristeria
https://en.forum.elvenar.com/index.php?pages/game_rules/  

Indeed, precisely for the situation you are bringing, the game rules do not allow you to share your accounts/passwords. It is one of the main ones, mainly for your very own protection. While you are at it, also take a look over the Forum Rules, as it is a great source to learn a lot about the game  

Despite the whole Password Transgression, what a mean and horrid thing to do  

The system clears inactive accounts, but it has several different aspects to keep into account. However, many inactive cities clear, turning into Gold Mines (gives you gold as per an NH visit). Eventually, a new city from a new player will appear there. However, we do not keep control of it, but the automated system.

However, as state above. Let's abide by the rules in the first place, ¡and we will not need to worry about our very own city deletion!  

Please then let support know about those breaking the rules @Timneh as per the Game Rules. It can prevent what has happened to many players who contact us in similar situations to Tristeria and it can be absolutely heartbreaking the devastation this can cause.  

I think as a general rule of thumb (but don't quote me) any Cities below Chapter 4/5 that become inactive are deleted/moved on the map to make way for new players. However if any Diamond Purchases have been made, the City becomes a premium city and remains for evermore.... Inactive Cities are a bit of a nemesis, certainly for Fellowships.  

That is correct @Pauly7 and it does actually happen, although a slow process.  

@cwgiii no worries as right now it is much more solid. As @Silmaril said, it takes its time (especially to avoid conflicts or miss-configurations.)