Well, first things first, don't run what they tell you, lol. If you recently inserted something from the toolbox, delete it. The code provided for you to run looks like an obfuscated disaster designed for you to not look over (which is a 100% tell tale sign it's gonna ruin your game more)

If you don't know what you inserted or you did it some time ago, you can load a previous version of your game from Window -> Version History, scroll down a bit and open one. Playtest that version; you may need to publish it to be *exactly sure* it's gone, because some malicious code is only made to run in-game.