You could cut them off with a grinder or a hacksaw or a junior hacksaw.
You could clean the cut end off with a file.
It would not damage the frame if you were careful not to cut into the actual tube.
Its your frame so if you don't want them on it, cut them off. Its not going to devalue anything and you might find it to be good fun and a good result.
Its only carbon steel anyway I dont think you would get more than £20-£30 quid with or without its downtube shifters.
You could cut them off with a grinder or a hacksaw or a junior hacksaw.
You could clean the cut end off with a file.
It would not damage the frame if you were careful not to cut into the actual tube.
Its your frame so if you don't want them on it, cut them off. Its not going to devalue anything and you might find it to be good fun and a good result.
Its only carbon steel anyway I dont think you would get more than £20-£30 quid with or without its downtube shifters.