Template:FormerAccount is to be placed on user pages of disused accounts to alert editors of a new username and to prevent wrongful sockpuppetry allegations.
Placed on the userpage and/or user talkpage of the old account, usage is as follows:
{{FormerAccount|<new account name>}}
Accounts could, for example, be disused due to loss of password when no email address (or an incorrect email address) has been set.