Like everyone said, dump the subprime cards when you qualify and procure prime cards and it no longer makes sense to keep the subprime card. If the APR and other terms work for you, there is no reason to rush to close it. Only bottom feeders should be closed expeditiously. Other cards it depends on interest rate, annual fee or lack thereof and other features like customer service. PNC for example has the BEST customer service EVER!!
If you are looking for a number to know when you have arrived at "Primeville", I'd say when your FICO score is around 680, the train is pulling into the station :-)
I've seen some FICO scores not much higher than mine with prime cards, but have also seen 700s not able to get prime cards..so at what score level is it realistic to close rebuilders/builders?
FICO score has nothing to do with it. People dump sub-prime cards when they get approved for better cards and no longer need the sub-primes. In my rebuilding from a score in the 500s, I have never had a card with an annual fee. I have stopped using cards that offer higher interest rates and lower limits such as capital one and household bank because I have been approved for cards with low interest and higher limits. Thats all there is to it.
I have secured CCs with 15% APR and will enjoy them long after I finally reach "Primeville". I'm not thinking about the deposit.