Problem in making subfolder to new domain

Too much confused now, very new to wordpress.Can’t find any working solution for my problem all over the web.
Assume that public_html folder point to http://www.x.com.I have installed wordpress under folder public_html/subfolder which point to new domain http://www.y.com.

My problem is when i try to open subpages of my domain http://www.y.com , the url should be http://www.y.com/subpage but i am getting http://www.x.com/subfolder/subpage.
What should i do to correct it