Open Facebook and go to your profile
Tap or click Friends
Select the pencil icon or More options
Choose Edit privacy
Set Who can see your friends list? to Only me
Save the changes
On mobile, open the Facebook app and tap Menu
Go to Settings & privacy
Tap Settings
Find Audience and visibility
Tap How people find and contact you
Set Who can see your friends list? to Only me
Check your profile from another account to confirm the change