Will my 14.5V USB-C charger destroy my 9.7 inch iPad Pro? The charger is the one for the MacBook (29W) and the iPad is the 9.7 inch Pro. Can they be used together without damaging the iPad battery?
This should be absolutely fine. I haven't tried it myself (yet) but Apple themselves state that you can use the 29W adaptor with the 12.9" iPad Pro, and other people have verified that it works (and doesn't cause damage). 

This all came out before the 9.7" iPad Pro was released, and it doesn't look like Apple have updated the product page for their USB-C to Lightning cable, but I'm certain it will be fine. I've charged many an iPhone with an iPad charger without cause for complaint. 

The device should only draw as much power as it needs/is safe. 

Sources

Testing Apple’s 29W USB-C Power Adapter and iPad Pro Fast Charging – MacStories

https://www.macstories.net/ios/testing-apples-29w-usb-c-power-adapter-and-ipad-pro-fast-charging/

USB-C to Lightning Cable (1 m) - Apple

http://www.apple.com/shop/product/MK0X2AM/A/usb-c-to-lightning-cable-1-m