We usually send friend requests and if it's not accepted it is kept in pending. 
If  there are lots of pending requests it may lead to block.
   
So this is a simple way to get those requests cancelled and protect your account from being blocked.

    Follow below steps :-

    1. Go to account settings.
    2. Select `download a copy` option.


    3. Choose `expanded archive` from the next page opened and enter your   password and click continue.
    4. Select `start my archive`.
    5. After a few hours you'll get the download link in your email.
    5. Download the file `facebook` and unzip it.
    6. Open the folder html and then `friend_requests.htm­l`.
    7. You can see the list of your friend requests and pending lists.
    Now goto their accounts and click`cancel request.

    That's all You are done now. Your account is safe.