Removing post and core ?

I have 2 front teeth with post, core and crowns which were fitted 30 years ago. The metal part at the top of the crowns is showing black and very unsightly and I wonder how easy it would be to replace the old crowns or if necessary the core, post and crowns. I am worried that I might loose the teeth.

I would be grateful for any advise,
Many thanks,

Phel

Typically easy to do