How do you take them off. I want to replace them, becuase they are too dull

 

...you can polish them. The process can be time consuming, but the more time you spend...the better the results. I did a 'quick polish'(1.5hr) on my roof rails last year and it did make a noticable improvement. Just try some metal polish(& elbow grease)on a small section of your moulding to see if it's worth the effort.