Vespa cosa 1 200 carburetor hose

Hi!!!

 

I own a Vespa Cosa 200 and i recently bought a Polini venturi SI 24/24 air kit. Everything went well

when I was mouting it, but i can't remove a rubber hose that is attached on the frame. Please help

me with some useful hints or easy ways to solve the problem. Thank you.

 

Greetings from Slovenia