It's possible to disable or reset these devices, of course. The issue, as you might guess, is that there's usually one person in a relationship (typically the man, according to Intel researcher Melissa Gregg) who installs the smart home devices and has a full understanding of how they work. This gives the installer control over the other person that can become dangerous if the relationship is abusive. And when neither the survivor nor their friends may know how the technology works, it may be difficult to recognize the pattern of abuse or find ways to stop it without completely removing the hardware.
Those subject to abuse can fight back by becoming more informed about technology and making sure to have some control over smart home devices. There are legal failings as well, though. Only some abuse methods may fall under existing laws (revenge porn using security cameras, for example), and it can be challenging to secure restraining orders that ban misuse of connected devices.
Whether or not the hardware makers can address this isn't clear. The NYT noted that making it easy to switch accounts could increase security risks. And if you let two people manage a device, how do you make it easy to remove an abuser's account without that abuser having similar powers? There's no easy answer, and the situation underscores the complex, frequently unexplored social implications of networked homes. For now, education and an insistence on access may be the best defenses against this technological abuse.
If you or someone you know are yourself in an abusive situation, the National Domestic Violence Hotline offers 24/7 support at 1-800-799-7233 and 1-800-787-3224. Live chat is available online from 7AM to 2AM Central Time if making a phone call isn't possible.