Is it safe to turn off dehumidifier by switching power off
Refrigerant cycle dehumidifiers have some sensitivities, and I would recommend operating in accordance with the manufacturers recommendations.

I operated several types of conventional and LGR commercial grade dehumidifiers for many years. I don't know what your machine needs, but there were several reasons why our machines needed to be operated properly.

Since we don't know which type of machine you have, we don't have enough information to tell you why it might be a bad idea to operate it contrary to the manufacturers recommendations. However, there are a few reasons why it may be a bad idea to unplug a unit rather than turn it off properly. There are additional reasons why turning the machine off and on via a smart switch could be a bad idea.

These reasons could include:


The need to dissipate heat before the machine shuts down completely (from the directions you quoted it sounds like your machine has a blower that operates for some period after the "Power" key is pressed)
The need to let the remaining water collect before purging the drip pan (depending on how your machine collects and purges water)
The need for a compressor delay between on-off cycles (many machines handle this automatically)
The need to protect sensitive electronics from voltage spikes