Close and Reopen Codespace
Environment Setup
Closing
The codespace time out after 30 minutes of inactivity by default. So if you are not too worried about the 30 hour/month limit, just close the window or the tab. Alternatively, you can open the command prompt (Cmd + Shift + P) and issue the Codespace: Stop Current Codespace.
Reopen Codespaces
You can see your Codespaces on github.com/codespaces/. There you can stop them, reopen them and delete them.