This expansion, the pop-up snippet is placed into the Walled City.cs script.
You can either:
- disable the sound ding of it, with changing the true tag to false on line 57,
- short the pop-up duration from 20 sec to less on line 56,
- completely disable it, with removing lines 51 up to 62.
(Disclaimer - if you are not confident how to edit a script file, it is recommended to not give it a try)
