Unfortunately, you're probably stuck with this for life.
Penal Code 211, robbery, is listed as a violent felony in Penal Code 667.5(c), which makes it a "strike" under the three strikes law.
If you had completed probation, you could move to have it dismissed under Penal Code 1203.4, which is sometimes called an "expungement," even though it does not seal any court records and does not prevent the conviction from being charged as a strike in any future case. However, because you were sentenced to state prison, you are not eligible for a 1203.4 dismissal.
You could apply for a governor's pardon, but you have no realistic chance of receiving one. California governors have only granted three pardons in the past ten years, all to people who were convicted on non-violent drug offenses more than twenty years ago. Even if you received a pardon, the prior conviction could still be used as a strike in any future felony case.
Under California's Three Strikes law, the sentence is increased if you are convicted of ANY new felony and the prosecution proves you have prior "strike" convictions.
Strikes are the serious felonies listed in Penal Code §1192.7(c) and the violent felonies listed in Penal Code §667.5(c).
If you are convicted of ANY new felony and ONE prior "strike" conviction is charged and proven:
1) You are not eligible for probation.
2) Your sentence will be doubled.
3) If your new offense is a non-violent felony, you will have to serve 80% of your sentence, instead of half, before being paroled. (People sent to prison for a violent felony have to serve 85% whether they have a prior "strike" or not.)
If you are convicted of ANY new felony with TWO prior strike convictions, the sentence is 25 years to life.
Please understand that this is a general discussion of legal principles by a California lawyer and does not create an attorney/client relationship. It's impossible to give detailed, accurate advice based on a few sentences on a website (and you shouldn't provide too much specific information about your legal matter on a public forum like this site, anyway). You should always seek advice from an attorney licensed in your jurisdiction who can give you an informed opinion after reviewing all of the relevant information.