Unfortunately no. I was also hoping it was just a matter of selecting 0.4.5 in the menu as well.
To go back to 0.4.5, I had to install the Particle CLI and then flash the 0.4.5 version to my device through the CLI. But in order to do that, it was a somewhat laborious process of installing all the supporting software (I don’t work with this stuff often so it was a learning experience).
I would start here: Tutorial: Particle-cli on Windows [07 Jun 2015]
I believe I got the 0.4.5 files (there’s a part 1 and part 2) from the github page, but honestly don’t remember where. I think if you search the forums there’s a guidance on flashing the firmware. Hopefully that helps!