Disassemble and remove the motor from the bottom of the shaft then slide shaft through steering motor.
Or try to remove the cover on the top of the motor shaft first, I can't remember for sure but I think all the electronics plug in there and can just be unplugged, then the shaft slid through the steering motor.
Why would you want to remove it anyways?
To remove the base, you'll have to take off both side plates (should be phillips screws if I remember correctly from my Terrova, this will allow access to the 4 or 6 bolts that physically mount the whole unit.
You don't need to remove the motor at all. There are two styles of Rip Tides. If you have a sissor mount, deploy the motor to access the bolts. On the electric steer version, remove the side panels and remove the four mounting bolts.