A friend would like to use one of the free email providers such as Yahoo or Google mail but has concerns about fully closing the account when it is no longer required. David J Jones
Free email accounts cost suppliers money, so they have no interest in keeping email around if the user no longer wants it. Most provide details of how to delete an account, and NSpeak has links for the big three services.
Some people worry about someone else using an account with the same user name, and therefore hang on to accounts they don't want. However, many people have the same name, and this may deprive them of something they would value. Also, anyone can "spoof" (forge) an email address even without having access to the account; hanging on to an address doesn't prevent that.