At the onset, let me tell you that on Facebook it is not possible to disallow everyone from sending you friend request. Facebook is a social network and it is all about connecting with people. So, just being there without having any friends would not make any sense.
However, you can limit the scope of people who can send you friend request. Some people don’t want to receive friend requests from people who are not at all connected with them. This could be accomplished on Facebook.
- Go to Privacy Settings
- Click the “Edit Settings” link given against “How you connect” option
- A box will appear. Change the value of “Who can send you friend requests?” from Everyone to “Friends of friends”
- Click Done
Now only those people who are connected with you through your existing Facebook friends would be able to send you requests. Totally unknown people won’t be able to send you friend requests.