Any time I get into deep snow or sand my traction control bogs down the power and beeps at me causing me to lose all my momentum and gets me stuck, I've owned Tacoma’s and never had this problem.

Does anyone know how to disable the traction control when I'm off roading?

It may sound weird but here are the steps. You have 60 seconds to complete the steps it dont take that long. Also I found out it dont matter what gear your in as long as you get the steps done within the 60 seconds. Note: It is not recommended to do this in gear for safty reasons. I have a few times after shifting out of park and then remembering I disable my traction control.
1. Start your car
2. Pull the E-Brake "dont matter how many clicks"
3. Push and Release the Brake Twice.
4. Release the E-Brake
5. Push and Hold the Brake
6. Pull and Release the E-Brake Twice
7. Release the Brake
8. REPEATE STEPS 2 and 3

If done correctly you will see the little skidding car light up on the insterment cluster. The brake or throttle back off will not be used when wheel spin is detected. Note: Doing this in the 4X2 V-6 will let you get better track times with the proper throttle control and wheel spin. Too much gas and you'll spin all through 1st gear.

Does the traction control automatically turn itself on at the next startup?

Sorry for the late response, I haven’t checked the site lately.

I will try this the next time I drive my Rav, and let you know if I was successful.

Later....

Yes once the car is turnned off it will return to normal operation. Also if you want to keep the TC Off then carefully/slowly turn the key till it shuts off and stop place key back in the ON position if done right the Skid light will stay on.