If you have too many credit cards to manage, you can simplify things by merging credit cards that are offered by the same bank. All banks do that for you in a single call. The credit card merger will give you one card that has the combined credit limit of both the cards. This will have no significant effect on your credit history if done correctly because your total credit limit will remain the same. This makes merging your cards a much better option than closing the accounts of unused credit cards. When the banks of two of credit cards merge or one takes over another, take advantage of that to combine credit cards.
Make sure you combine the credit cards into the card that has better benefits (better rewards, lower fixed APR or whatever criteria are important to you). However if your credit history is not very long (under 5 years), my suggestion is to combine both the cards into your older card because it is generally not advisable to close down old credit card accounts.