Follow below step

PS: I kindly advise that do not erase everything like this step said since the info from other of your projects could be in the same folder and being deleted alone with this execution.

1) Clean Derived Data as show below,

rm -rf ~/Library/Developer/Xcode/DerivedData/OR

Xcode---> Preferences--->Location--->Derived Data

2) In Deployment Info change Deployment Target

It's equal to or less then the SDK version of Xcode

3) Quit Xcode

4) Reopen Xcode you will see list of simulators

Hope this is help for some one.

ref: https://stackoverflow.com/questions/26690730/xcode-project-not-showing-list-of-simulators