I'm rewiring sections of our house and need an extra slot in the panel. The dryer is wired to a tri-pole 30 AMP breaker. I have never seen this before and was wondering if I can swith it out for a 2-Pole breaker. There are three wires coming from the dryer - Red and Black to the breaker and white to the bus bar. Thanks.

If they used a 3-pole breaker in place of a 2-pole then certainly, you can remove it and install the proper 2-pole 30 for your dryer.

LOL they had that 3 pole and they used it to get rid of it. That is so stupid, That breaker worth lot more money, try selling it to a commercial electrical supply or on eBay.