If you have previously recommended this thread, you should see a tick / check mark on the recommend button. Click the tick to undo the recommendation (the tick may appear to change to a cross as you do this.) If you added a comment with your recommendation, you will need to delete that from your facebook wall separately.
DS did this at nursery with toy cars. He had a lovely teacher who talked to him about how sad it made her feel when the toys werent there at nursery for all the children. I checked his pockets at pick up for a while and looked serious but I think overall nobody thought it was too awful, they are only little at 4.