Because if you delete your account - it can mess up threads that you have posted in and it is something that's very time consuming. If you don't want to access your account anymore they you can always change your username and reset your password to a jumble of letters so that you won't be able to log back in.
To contact the mods either PM someone with a red username or email them at
moderators@recoveryourlife.com
They very rarely delete accounts though unless you have a very good reason.