My business partner is buying out my interest in the current company and I need to transfer certain domain names into his possession. How do I go about transferring these domains from my personal accont into an account he establishes?
I would have thought if your business partner was 'buying out your interests', then giving away your domains wasn't actually buying out your interest.
Sell him the domains! Simple.
Of course this only works if you have not declared bankruptcy and then there are rules against 'giving away for free' company assets.
Or you could simply put his bank details and address etc in billing details and then you will be able to remove yours, but only while there is at least one payment method in place to pay for current services.
Then it's an easy route to giving him your passwords etc, which he can then change.
Support will be your best resource here. Give them a call.