Problem with winterizing sand filter for above ground pool

Have an 18’ round above ground pool and now that weather is getting cold now’s the time to winterize filter. I am a first time pool owner. I am having a real hard time disconnecting plastic pipes from filter pump. What’s the secret?
New question…Also no trees near my pool only a few pine trees about 12 feet away…do I need to cover it for winter? Water is balanced and lowered. Pool installer said no…but I need other opinions please.

thank you