didn't think so but was hoping I was missing something! there should be an option to right click anything in history and remove just that edit. oh well......
I'm not sure if this is what you mean, but there is the action list on the bottom-right. For example, a typical workflow for me in RX will be Declick > Gain > Spectral Denoise. Each time I process / render one of those modules, it adds a step to that list. If I want to go back to an earlier state in my processing sequence, I just go back and select it, and it recalls that state.
As long as you save your session with that file when you close RX, you should be able to access this recall list.
Obviously, once you export your processed file as a new file, you can't undo anything in that new file.