How to get rid of blank space

There is a blank space on my forum (you can see it on the picture below). How can I get rid of it?

Hi,
Can you change the permission to guests?

I don't see your problem

One (the largest one) of those spaces are for ads.  To remove it, you will need to use credits to remove the ads.

It's okay now, I already figured everything out. Thank you!

You can lock this topic.