can I change from IMAP to POP without reinstalling?


You can, but you’ll need to back up your IMAP mail folder to your local folder first. After backing up you can change the server setting from IMAP to POP if your mail provider support both.

There is no need for reinstall. You will need to create new account in menu Tools->Accounts, click New account, click Other in Mail section where you will set up your account as a POP3 account with its POP3 settings. But only special folders (Inbox, Sent,…) will be displayed with POP3.

If your admin configure to enable IMAP for your email user , the eM client automatically use IMAP, you do not have option to disalbe IMAP and use only POP3 by the eMclient software.
This (IMAP) means that your server mailbox will remain the same as on your desktop eMclient mailbox; and of course it will soon be exceed quota (full).
I suggest eM client should allow user to choose using POP3 or IMAP when they create new account.

You can choose when setting up a new mail. At new accounts, use Mail -> Other instead of ‘Automatic Setup’.

At step 2, where you set Incoming server, there’ll be an option for IMAP or POP3.