connectors

I have the Logitech Z533 speakers and subwoofer set, however my subwoofer has yet again died (second time in 3 years, wouldn't recommend). The speakers are fine, however they do connect to the sub which I believe has a small amp within that drives them. I'm pretty sure they're 15w per speaker...

I get a bit jittery when I'm unplugging cable connectors (these images are just examples, I'm thinking of all types of connectors). What's the best way to safely unplug them?, pull from the cables or from the plastic case. What's your experience? http://i.imgur.com/lUllecb.jpg...