When you make the decision to cancel a credit card, you can't just grab the scissors and just cut. you need to take two major steps. Doing these two steps will ensure that closing your credit card impacts your overall credit report as little as possible.
Be sure the credit cards are listed as closed on your credit report.
If the report still lists the account as open, then it may reduce your chances of obtaining more credit or getting a loan down the line.
Ask for written verification that it has been cancelled.
It would be wise to request a credit report from a credit bureau one month after cancelling your credit card. If the report still shows the account open, then let them know and send a copy of your verification letter that validates that the account is closed.