Open Facebook and log in
Go to your profile
Click or tap Friends
Click the three dots or Edit privacy
Select Edit privacy
Set Who can see your friends list to Only me
Save your changes
On mobile, open the Facebook app
Tap the menu icon
Go to Settings & privacy
Tap Settings
Tap Audience and visibility
Tap How people find and contact you
Tap Who can see your friends list
Select Only me
Confirm the change