Frame arround picutures

Hello, i'm not able to remove the frames arround the pictures. I found this soulution in the forum: https://catchthemes.com/support-forum/topic/frame-around-pictures/ But this solution works not for me... Here an example from my webpage: http://web55680.greatnet-hosting.de/ralf-becker/ i want to remove the frame arround the picture... and from all other pictures on this website. Thanks for your help!