What is a one-sentence summary of the following article?
The Facebook app looks like a white "f" in a blue square icon on your home screen, or in a folder. This button is located in the lower-right corner of your screen. It will open your navigation menu on a new page. This option is located towards the bottom of the menu. Your options will pop up from the bottom of your screen. This will open your Settings menu on a new page. On some versions of the Facebook app, you will see a Chat Settings option on the pop-up menu here. In this case, select this option. This option is listed next to a gray speech bubble icon. Turning off this switch will disable mobile chat on your iPhone or iPad. You will appear offline to all of your friends on Messenger.

Summary:
Open the Facebook app on your iPhone or iPad. Tap the three horizontal lines icon. Scroll down and tap Settings. Tap Account Settings on the pop-up menu. Scroll down and tap Chat Settings on the Settings menu. Slide the Chat switch to .