Hi Andrea, welcome to the community
You have a relatively straight forward switch over ahead of you, so no worries
As you've already mentioned, the thick orange wires going into the 24VAC terminals, as well as the thick green wire going into GND terminal, should be disconnected, you will no longer require any of them.
Don't worry about the yellow jumper wire connected to SENSOR, that is just how your rainbird used to operate, it does not look like you have a rain sensor.
You have two white common wires, I'd recommend to connect them to separate C terminals of your new Rachio.
You also have two Master Valve wires (now sure why two, but it is what it is). Connect both of them to the M terminal of your rachio (I would twist them together if possible and connect them as one). Do not forget to enable master valve within the Rachio's setup.
Finally just go down the line and move the zone wires from rainbird's terminals 1 through 9 to Rachio's terminals 1 through 9. Order should not be critical here, you will probably end up renaming the zones during the Rachio's setup.
That is about it,