Changing colour of patterns

Hi there

I am wondering if someone can guide me in the right direction with regards to a Photoshop problem i have.

Basically i have a photo of a large fabric chair which is purple and has large green leaves on it. I need to change the design/colour of this chair so that it is purely cream.

If the chair was just purple then i konw how to change it to cream, but im not sure how to go about changing the actual pattern of the chair?

Is there a way i can change the green leaves and the purple background so that the whole chair is just a cream colour with no pattern?

thanks for any help