Once the Chat option is turned off, the only way to guess your availability on Facebook will be by the status updates that you may post on your timeline, or due to any activity that you perform as it is displayed in your friends' newsfeeds.
In other words, if you turn off the Chat option on your Facebook account and don't do anything, you will remain completely invisible to all your friends until you manually turn Chat back on.
Here’s how you can turn the Chat option off and make yourself invisible on Facebook:
- Turn on your Android phone.
- Tap the Menu button to go to the apps list.
- Locate and tap the Facebook icon.
- If you are not logged in, provide your correct credentials in the appropriate fields, and tap the Log In button.
- From the News Feed page that opens up, tap the Chat icon in the title bar from the top-right corner of the interface.
- From the chat interface, tap the gear icon located at the top-right corner of the screen.
- Once done, tap to uncheck the On checkbox in Facebook chat box that opens up.
- Finally tap the back button to return to the previous interface.