You can safely disconnect a laptop from the power source from either end. Power adapters are safe piece of hardware that must respect international regulations and won't spike when disconnected, or otherwise damage your computer.
However, a laptop power cord can be a safety hazard to adults and children alike, and even your computer. It's a lengthy cord that can be tripped upon by someone. Disconnecting from the wall, but leaving it attached to the laptop may drag your laptop with it, if someone trips on the cord. Conversely, leaving it around attacked to a wall outlet, may become a problem to people walking close to it.
Ideally, it should be disconnected on both ends, and stashed away. But being that not convenient for whatever reason, make sure it's at least disconnected from the laptop end and shoved against the wall, or otherwise out of other people harm's way.