Yes you are able to take them off, personally i pick mine ones off. The Ergot is made from the same as the hoof and chestnut, so can be removed, Some farriers will happily take them off if you ask. I prefer picking my guys ones off, feel it is safer than hacking at them with a cutting instrument!! Good luck!
I twist my boys ergots off, sometimes it is easier than others and yes, agree with Elane, it is easier if you soak them first so I often do it when I have just bathed them
It is fine to remove them - just be carefully doing it - if you remove too much, they really bleed. My pony has feathers, so I leave the ergots, but did once pick off a bit of chestnut and it pulled off a really deep bit and it bled quite a lot! Gross!!
My farrier removes the Ergots on OH's cob. He only trims a little bit at a time. He did have hairy legs but since he was turned out as a Show Cob and his leg hair clipped we had to also remove his long Ergots! He is looking smart now though!