This problem is well documented but your dealer can't legally disconnect the evap canister system.
There are several threads about how to do this yourself. There's a current thread where a member who has a GT200 (carb model) has disconnected his. The procedure is pretty much the same for the fuel injected model. Read the thread and if you still have questions, post them here.
Here's the thread:
https://modernvespa.com/forum/topic49615