You can design your Games or Movie with Unreal Engine provided by EpicGame. It's a great software but sometimes when you install the the Epic Game launcher it doesn't get installed properly so when you start it won't show. So the suggested step by EpicGame is to uninstall and reinstall it again. Following are the steps to uninstall and remove all the left overs

You can find a complete documentation here 

1. Close the Epic Games Launcher.
2. Verify there are no processes associated with the Epic Games Launcher by checking Activity Monitor.
3. Open the Applications folder.
4. Click and drag the Epic Games Launcher application to the Trash.
5. Verify all the following directories no longer have any Epic Games Launcher folders or files:

• ~/Library/Application Support
• ~/Library/Caches
• ~/Library/Preferences
• ~/Library/Logs
• ~/Library/Cookies

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