Katherine Jackson has filed to resign as Blanket Jackson's legal guardian.

The 87-year-old matriarch of the Jackson family has formally started the process of resigning as the co-guardian of the 15-year-old son of her late offspring, pop icon Michael Jackson.

As a result, T.J. Jackson - the youngest son of Katherine's son Tito - who previously served as co-guardian to the teenager, will eventually become his sole guardian.

The duo also previously served as the co-guardians for Michael's two eldest children, 20-year-old son Prince and 19-year-old daughter Paris.

Paperwork filed at Los Angeles County Superior Court reads: ''Katherine is no longer needed to fulfill the duties that were necessary when joint-guardians were appointed on September 14, 2012.

''Given her own age and the fact that [Blanket] is now 15 years old, Katherine feels that T.J. is able to assume all necessary responsibilities the guardianship. (sic)''

Following Michael's death from acute propofol intoxication in June 2009, Katherine became the guardian to his three children.

However, T.J. was appointed co-guardian in 2012 and earlier this year, Prince revealed his cousin has been a huge source of strength in his life.

Prince - whose mother Debbie Rowe also had Paris with the musician - explained: ''When my dad died, the thought of being in the foster system crossed my mind, but I was fortunate to have an incredible grandmother and cousin, T.J., to fall back on.''

Meanwhile, it was recently reported that Blanket - whose full name is Prince Michael Jackson II - had ''the most problems'' coping with his father's death.

Although all of Michael's children were deeply affected by their father's sudden death in 2009, it was his youngest son - who was seven at the time of the pop star's passing - who found it most difficult to come to terms with.

A source close to the family recently said: ''[Blanket] has had the most problems adjusting after Michael died. He acted very lost and extremely upset.''