How to remove non existing page?
Example 1 is node 5 (http://erlinevanhijfte.be/node/5). go to it and delete it.
Example 2 is node 102 (http://erlinevanhijfte.be/node/102). go to it and delete it.  

To find the node I just looked at the page source which has a shortlink meta tag which shows the node id and also the body tag has a class which shows the node id