1) You are allowed to downgrade your account. I once did it. You can start here with this link:
https://www.paypal.com/us/cgi-bin/webscr?cmd=_help-ext&eloc=147&loc=131&unique_id=1405&source_page=_account&flow=
(2) but the instructions on that page seems faulty to me. Maybe they are trying to make it hard to do.
(3) incidentally, you can have two PayPal accts with different email addresses, etc -- a Business/Premier one and a Personal one.

Good luck,
Robert