Most of the people at my office know of my Stack Overflow account. This account (workplace) is associated with my SO account. However, I want to remove this association as this is a danger to my job. I have asked certain questions on Workplace about my job which can get me into trouble.
It is no longer possible to disassociate one account from another, since accounts are now network level.
Since all associations are done through credentials, disassociating* doesn't really make sense anymore. It's roughly equivalent to "delete this account", as removing the "associating credentials" would leave the user unusable.
So, in short, it is no longer possible to disassociate accounts.
*The associate button is still available for debugging purposes, it will be going away eventually
It is, however, possible to remove association at the post level. If you've got a particular question or answer you'd like disassociated with your account, flag it for moderator attention, and explain that using the "other" option. We will contact the devs to anonymize it (example).
If you don't want future questions associated with your account, you can log out (or use a different browser/incognito browser window) to ask the question as an unregistered user.