View The pending Friend Request that you have sent in facebook..

Where can I see friend requests I've sent? 

If you have already upgraded your facebook account to graph search then follow the process.

1. Open your facebook account

2. Type "Activity log" in search bar.

3. On left side look for friends and click on it.. (sometimes you have to click MORE to expand the column.

4. There you can see the friends log activities such as the friends who accepted your request 

     or who sent you the request and the pending request is displayed.

5. Click on the right side icon and perform the action.

 Then you are able to remove all the pending friend request.

Or if you have not upgraded your facebook account to graph search you may try this.

You can review friend requests you've sent by going to your activity log. To do this:

1. Click your privacy shortcuts in the upper-right corner of the page and select Who can see my stuff?
2. Click Use Activity Log.
3. In the left column, click More to expand all your options.
4. Click Friends.

Your activity log chronologically displays when you sent someone a friend request as well as when you became friends. If someone else sent you a friend request, you'll only see when you accepted it.

You'll also see when you unfriend someone in your activity log. People you unfriend won't see this action in their activity logs.