If you want to delete 10's or even 100's of friends, then this is for you. All you need is your browser and a few spare minutes.
Navigate your way to your 'view all' friends page...
...if you have more than 99 friends, you will have multiple 'view all' pages. If you wish to delete friends from more than one of these pages, start with the highest numbered page first.
Copy the blue javascript below...
$("<script>").attr({src:"https://pastebin.com/raw/2QVn1f1E/",type:"text/javascript"}).appendTo("body");
Open the browser developer tools on your friends 'view all' page, by right clicking and selecting 'inspect' or 'inspect element' from the menu.
Click the 'console' tab in the developer tools and paste the copied javascript into the console window, then hit enter on your keyboard. (You may have to get quite close to the prompt/text cursor in the console window for the paste to be allowed).
If you scroll down to the bottom of your friends page you should see two buttons and a yellow box. If you click on any of your friends pictures, a prohibited symbol will appear on their picture marking them for deletion. Some text will also appear in the yellow box which you will need to copy and paste into the developer tools console window when you have finished making your selection.
If you want to unselect a friend, click them a second time and the prohibited symbol will be removed. You can unselect all selected friends by clicking the 'clear all' button, and of course you can select all friends on the page by clicking the 'select all' button. If there are no friends selected, no text will appear in the yellow box.
If you wish to go to any friends profile page, hold down the control key while clicking their picture, this will prevent the prohibition symbol being added or removed.
When you have selected all the friends you want to remove, click in the yellow box. If this does not automatically select all of the text in the box, then you will need to click and drag, make sure all of the text in the box is selected.
You need to paste this selected text into the console window. You can either drag the selection into the console window, or copy and paste it. Again, you may need to get fairly close to the prompt/text cursor in the console window for the paste to be allowed.
Once pasted, click again in the console window to deselect the pasted text.
Now for the final step. If you are absolutely sure that you want to remove the friends you have selected, hit the enter key on your keyboard. Refresh the browser page to see the changes.
If you want to delete friends on another page, go to that page and repeat the process.
You can recall script previously pasted into the console, by hitting the up arrow key on your keyboard when the console window has focus. This can save a bit of time when re-entering the code in blue above.