Child for all these years and now she shows up wanting to take the child away from me, is this possible? I have my first court hearing in a few days and I just filed for adoption of the child.

I don't know why you would doubt if you are the 'legal guardian'. In what way are you the legal guardian, are you the court appointed legal guardian, because in this case, no she can't take the child away from you. Are you the legal guardian because she signed away her riights to the child and that is how you are able to adopt?

Tick

I was appointed by the probate court in California. But I don't know if she can get the child back because I haven't adopted her.

I don't understand your relationship to the child, though, were you married to her mother and you are the stepfather, or are you the bio father, but yes, you were appointed legal guardian by the court, so there is nothing she can do to circumvent that. You will need a lawyer though.

Tick

Once the guardianship is established, it will remain under the supervision of the probate court until the child turns 18 or the court terminates the guardianship, whichever comes first.

The fact that the mother has gotten a court hearing, does not mean she will win, but then we do not know why you were given guardianship, was there reasons, and more. Could the court give custody back to the mother, yes. The reason why she did not have it to start with, how long it has been, and other factors, You should have an attorney to represent you.

As GV noted the probate court established the guardianship and it will be up to them to end it. Whether they will decide to end it depends on a lot of factors that you have not given us. You ask "is is possible?". The answer is; yes it is. How possible we can't even begin to judge without much more info.

We need to understand the circumstances of why you were awarded guardianship. Your relation to the child, the age of the child, where is the father and more may be necessary.