Hi Gerd. A number of Cyclamen have perennial roots and it's best not to cut healthy, living roots as the plant will just have to expend energy growing new ones. By cutting you could also open up sites for infection. The roots on your plant all look to be healthy and alive. If there are any obviously dead roots (dry, brittle, rotting) you could cut those out to a point where there is healthy tissue (may dusting with a suitable fungicide). Otherwise leave them.