how can i delete the wrong line in the geometric

Hello Felix,

This warning message arises since the line is used by another entities, most likely by faces or volumes. You can check these usages by using “find usages” command. I advise you to check these dependences carefully before deleting your line. I advise you to delete first all the entities using the line and them delete the line itself in the usual way.  

Another possible solution is just use the command 'force delete' over the line, instead of 'delete' command. It will works and all the entities depending on the line will be also deleted. Anyway, I only advise you to use this second method once you are totally sure about what entities are using the line (and, thus, what entities will be deleted).

Best regards,

thanks, Alejandro!