Hello,
First, go to Settings > Accounts > Sign in options, scroll down to mid page, Do you see "For improved security, only allow Windows Hello Sign-in for Microsoft accounts on this device (Recommended). " If so, make sure it is turned off before you can remove PIN.
If that still doesn't work, Can you go to your Windows Settings > Accounts > Access Work or School (note, it is the briefcase icon, not the envelope or little person icon). Then see if the organization email address is still listed? If so, click on it and then disconnect it. Restart the computer and see if you can remove PIN.
If for any reason this still doesn't work or you cannot find the organization account, or the option to turn off requirement of Windows Hello, type "regedit" in the search on the taskbar to launch Registry Editor, then go to this folder on the left pane (use the little arrow on each folder to expand), and share a screenshot so I can review.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\PasswordLess\Device