How to remove a duplicate account address that is freezing all account settings

A duplicate of my account name--karenandal@comcast.net--has appeared in the left pane. It is called "a special account" in its settings box. I cannot use any of the settings in my regular account. A message box reads: "An account with this name already exists. Please enter a different account name." When I open the settings in this duplicate account name "Remove" is gray and inoperable. A small blue tv image icon precedes the duplicate in the left pane. My regular account is preceded by a mail icon. I don't know how this duplicate of my account name got there. But I can't change any settings on my regular account. Please help me. Albert Spanfelner