I ran into an issue recently where I was trying to debug a problem in a project, but had a problem accessing the right data server since I was logged into a local development server, and really needed to get back to the “new app” state.
I searched for “reset xcode simulator” via DDG and first hit came up with https://stackoverflow.com/questions/16195859/reset-ios-simulator-application-data-to-run-app-for-first-time#16195931 which gave me an answer.
The command line versions work, but it can be a pain to get the UDID for the simulator. Doing it from the running simulator was easier, but of course the menu options are different than discussed in the stackoverflow answer.
I found it on the Simulator (Version 10.0 (SimulatorApp-835.2.1) seen in the following screen shot: