Tito Jackson -- I'm Backing Out of My Siblings' Plot

Tito Jackson is backing out of the plot to turn Katherine Jackson against the Michael Jackson Estate ... he tells TMZ he wants nothing to do with it.

Tito says, "I completely retract my signature from the July 17th letter sent to the Executors of my brother Michael's estate and repudiate all the claims made against them."

He adds, "I don't want any part of that letter whatsoever."

The letter Tito is referencing was signed by Jermaine, Janet, Rebbie and Randy ... and accused the executors of failing at their job and stressing out their mother, Katherine Jackson, so badly that she suffered a "mini-stroke."

We broke the story ... Tito's son, TJ, is preparing legal docs so he can ask a judge to become the temporary guardian of Michael's 3 kids.