Open the Outlook app.
(This is the reverse process of 'removing the users' profile from the Outlook App')
Once the Outlook app has been opened, the 'Outlook' option in the top toolbar needs to be selected.
Following this, the 'Preferences' option in the list menu needs to be selected.
Once the 'Preferences' option has been selected, the 'Accounts' option needs to be chosen.
This will bring up a list of accounts, which should not contain the user information for the one who has had the issue.
The new account needs to be set up as an 'Exchange or Office 365'.
A credentials box will then appear, in this the client will need to enter their username and account that they wish to create.
Once entered, there will be an Office 365 prompt box that will have the username in, but the password needs to be entered. Once the password is entered the user should have access to their Outlook inbox.
If the original credentials box says 'Authentication Failed' - or the Office 365 password
box keeps appearing the deletion of passwords has not been fully completed.
If the user can view their Outlook inbox, wait a few minutes to see if the password is asked for again. If it does not appear then 'Quit' the app and reopen it to double check. Then send a test email from the users' account to your own to check whether the account can send emails.
Once the Email has come through, send a confirmation Email back and then once that is received the process to stop the password prompt issues is complete.