Delete unused/inactive images

Hello,

My name is Olle Dahlquist and I live in Boden/Sweden – 100 miles south of the Arctic circle.
Yes, we still have summer and no ice bears on the streets.
My profession is graphic and web designer since 1994.

My problem is that I have been forced to take over a web site made with MySQL (?), CPanel and WHM.
This is kind of new to me and I have managed to do some changes.
Now I see that the images in the Upload-folder takes 130 MB of the 250 MB that is provided by the host. In all 249 MB is used by images and e-mail.
Now I am looking for a plug-in that can delete all unused and/or inactive images.
As I look in the sub folders I see all kind of versions of the same images, and I don’t know which one to delete.

I have tried to download some plug-ins, but as it says in the instructions I should activate the plug-in on the WP-menu, but I can’t fins anything like that under setings. All I can see clicking on the settings is “Always open this directory…” and there is no WP-settings as I can see. The directories are named WP-admin, WP-content etc, so I guess it is a WP-site.

All help is appreciated and I am sorry if this is a to simple question for you experienced users.

Kind regards,

/Olle Dahlquist