How do I get rid of a pop up from an old server account

[Jessie]

I have this pop up that appears everytime I access my MS Outlook. I changed
my ISP provider, but the pop up states - Enter Network Password, and it is my
old ISP server etc. How do I get rid of this? Please be kind I am just an
end user.

 

[DL]

Select Accounts, within outlook, remove the old account.
For your current mail account ensure the correct connection is selected.

Also, in Internet Options, ensure you are using the correct connection