Plugin installation went wrong

Sorry for bothering once again. Our forum has been up and running and we already fixed all the issues we had with emails, privacy, etc. and thought we’d add some plugins by following this guide. Right after we completed the last step, our site completely died and we’re getting a This site can’t be reached error.

Any tips on how to revert to the previous state or how to remove the plugin?

Thank you.

To remove a plugin, remove the corresponding line from your app.yml, then run another rebuild.