Best way to decommission a dev version of a site?

Hi - I created a site at a separate subdomain (eg clientsite.dev.mysite.com)... then duplicated the site which is now hosted on their domain (eg clientsite.com).

I was wondering what I should do with the original dev site now that we're launched. Should I just delete the thing? I guess if I need to make a staging version some time in the future I can always do the opposite, ie, create a copy of the live site and put it somewhere else.

Just wanted to know if anyone had any tips on this topic, thanks.