Point folder where site is install to root.

[nci]

My site www.nigerianscomplain.com/forum

[binaryg]

You need to either install in your site root or do a 301 redirect

[snakes1100]

1. Move all files and sub dirs from /forum to /public_html or root
2. Change URL settings in the admincp --> vbulletin options --> site url settings
3. Make sure you style options for images also reflect your move if they are hard coded in.

Thats all you need to do.