As shown on the picture, I am currently displaying topics with a picture. It's been like this by default and the picture is either blank or if an image has been uploaded in the thread, it's that image. However, I would like to remove this and haven't been able to find the setting to do so. Could someone please help me by letting me know how to display topics in the list without these images?

If you open up the page editor, then click on that block, you will see a menu open at the bottom, where you can select to hide images

Just now, Marc said:

If you open up the page editor, then click on that block, you will see a menu open at the bottom, where you can select to hide images

Thank you soooo much! I didn't even notice that menu!!!!

No problem at all. Its well worth exploring those menus, as you can achieve quite a lot with these. You may also find the following guide of use to you