Deleting Information Window

[mungee]

This topic has been discussed on this forum a few times now.
I have tried what one is supposed to do ie Alt + righ/left click in the grey box (top left of screen) ... but nothing happens - the information window/box isn't selected.
I've also tried creating a new Information Window - I read that you can sometimes have success removing the information box if you create another one and then delete the two!?

I would appreciate some guidance here - it's annoying me seeing that grey box in the corner of the screen.

Many thanks.