I just ignore them and they go away on their own.
Commercial vaccine(if it's still even on the market) is a crapshoot.
If you think you've gotta do something... mash 'em with a pair of pliers 'til they bleed... or just grab 'em and twist 'em off.
The old timers would say tear them off and make them eat 'em.
IF that actually worked it was probably from making them bleed when they ripped 'em off.
The idea of making them eat 'em most likely was thought of as being a crude method of vaccination.
Rarely do I see them in the older cows but my heifers tend to get them and they just go away. I did have one bull that had them on his, you know. Even took him to the vet but he earned himself a ride on to the sale barn.