Depends how they were installed. If they were press fit when installed you may be able to get them off. I usually epoxy mine on so they are a little tougher to get off...
You can make a ferrule removal tool by taking a piece of hardwood and drilling a hole the diameter of the shaft about 3/4" from the edge. Then cutt a groove the same width as the hole to make a U-channel so you can slip the board over the shaft. The hole you drilled should fit snugly against the ferrule on the shaft. Put the shaft in a shaft vise and gently heat the ferrule with a heatgun (on low!) or a hair dryer. You don't need much heat, just enough to soften the ferrule a bit. Slip the board over the shaft snugly against the ferrule and tap it off with a hammer. You may have to reheat the ferrule a bit as you go -- don't use too much heat, be patient and go easy.
I've used this method to remove ferrules I wanted to save. It's worked about 90%+ of the time.