The last time I installed a class 2 transformer it didn't have any disconnecting means on the secondary unless you want to take out the inline glass fuse which probably qualifies. You can turn off the breaker connected to the primary.
Most Class 2 transformers are plug-in (wall warts). For the occasional hard wired one, a toggle switch would suffice. Don’t forget, Class 2 means it is LESS than 100VA output. So at 120V, that’s less than 1A on the primary side.