Cannondale uses both pressfits and threaded bottom brackets. Hopefully his uses threaded.
Most cranksets employed by them utilize a self-extracting arrangement, either driveside or non-driveside.
My 8mm allen sits on the driveside. Turning it counterclockwise with the outer ring on will allow you to self-extract.
Sometimes these get torqued on at tremendous tightness, so you may need a large breaker bar.
I like socket keys to attach to a humongous ratchet handle.
It helps if you can get someone to hold the bike, while you hold the other crank arm firmly.