Are you using a gray card for white balancing?
Very colourful; I do not understand what is wrong with the bench? The photo is great as it is but white balance is important in every case; I don't think it is an issue here and it looks fine to me.
Maybe if you chose a different white balance it would look less purple, but I thought that was intentional.
By the way, the bench is away from the path and toward the bush, actually too close to the bush. May be there was not that much bush when it was installed but then they invaded forward...It was just a joke to distract you from the off balance WB but obviously it did not work!
I can see a strong magenta cast running right through it (eg in the tree trunks). It's something that takes while to learn how to spot.
Do you mean HOW? If so - two ways I use. In ACR just use the WB controls as per normal - in PS "proper" the way I prefer is to use LAB mode and change the starting points on the A and B axis in a curve layer.Also, who do you change WB of Jpeg in PS?
Auto WB works fine most of the time but it can 'throw a wobbly' when the colours are a bit unusual. In this case it possibly mistook pale yellow for white.
Could the bench be facing that way because there is an interesting view in that direction when the leaves have fallen.