most of us dont know how to hide friends
1. First of all sign in to your Facebook account.
2. On the top-right of your page, click the “Account” Tab. Select the third option, “Privacy Settings”.
3. Click “View Settings” which is under the “Connecting on Facebook” label. Here you will find different settings in which you can configure how your friends can find and connect with you.
or you like to hide them in chat
click on available chat