Forum Thread
Friendlist
Forum-Index → Suggestions → Rejected → FriendlistSo support or No Support?
It's not a daily scenario that you have to delete dozens of your friends o.O
By the way, you can also use CTRL + Left mouse click on the -icon. This will open the new window in another tab instead of refreshing the whole page. This is kinda just as fast as selecting them with checkboxes.
It'd be quicker to right now go through your list, even using the method Riako mentioned, and start deleting now as apposed to waiting for this feature to be implemented.