They come off quite easily unless it is an old light and the sticker has been "baked" on. If any sticky residue is left, there are "sticky label remover" products which are useful for safe removal of most labels.
I actually quite like these dot stickers, and I bought some packs in different colors for my A2s, including some exotic colors such as violet, orange, amber etc for when I get my Aviatrix mods from that crazy Ol' Bird.
If you have LED lights in different colors, these dot stickers really are quite useful to help identify which is which.