Power supplys aren't fragile like hard drive, it takes a hammer or a short circuit to break them (or a few drops of water...).
You can shake a PSU as much as you want and it won't break unless it flys out of your hand....
more likely to damage the floor than the power supply.
best to unplug the leads if they are tight though, if there is plenty of slack then no need
best to pull power cable though as there is still power going to the power supply
don't touch anything on back of powersuply, just pull cable
some power supplies have a switch/slider to convert from 110 to 230 input voltage
if you acidently change this then you will fry it (i know ive done it before, no pics this was before digital camera's where commonplace)