Well after reading your post, I have to say that it's likely not going to be easy but it is possible. over time a culture of needing their advice has made it so that they are conditioned to expect that this is what the relationship dynamic is. As parents they are merely trying to continue to support you but have not been given the feedback that now that you're older, and things have changed that their role needs to change.

I am guessing sometimes what you need more than anything is a listening ear rather than advice and solutions?

I would in times when it's calm, and not in the midst of a crisis or hardship of some kind, have a talk with them outside the context of anything related to your issues. what I mean is, take them aside and explain. the critical thing here is that you do it at a point when there is no stress or crisis involved or you're apt to be too emotionally charged to get your point across rationally.

Sounds like since you seem to have a generally good relationship with them that their is a high chance they will understand what you are trying to say, given that you do it at at time when you see eye to eye the best.

I hope this helps.