No, it is not possible to change an imap account to pop under account setting, otherwise I would not ask.
By creating an account you have to choose imap or pop, but later you can not change this.
My question is, how can I change an imap account to a pop account and not how can I create an imap or pop account?
It will depend on the account as well. Depending on how the server is set up, the account may be POP or IMAP only.
Delete the account and create it again, there is no way to change it once it is created.
In the account settings.
http://www.hosting.com/support/email/add-imap-email-account-in-microsoft-outlook-2011-for-mac-os-x
You really could google these questions yourself and get your answers faster.