Restoring removed portal user?

Hello,

I’m unsure what the process is for removing and then re-enabling a portal user? I’ve tried simply disabling and re-enabling a portal user but they don’t get a new email with a username and password. Also, if I manually create a user within the Joomla control panel, how do I then link this back to a contact record?

Let me know if what I’ve asked isn’t clear and I’ll try and explain it better.

Many thanks in advance!

Oliver