If you've got a Samsung SRF680CDLS fridge with water filer and ice maker the water filter has what might appear to be an easy to grip end piece for unlocking and locking it in place.
Sometimes it isn't easy to remove. The design means it's difficult to properly get a good grip on the water filter to turn and unlock the water filter from the fridge.
I've never turned the water off to get to the water filter, some sources online say you should in order to release the water pressure on the filter which will let it release easier.
In the past I've been able to change the filter fine without needing to turn off the water needing extra grip as explained below.
How to unlock the filter
You need something to grip it, although not pliers, I considered this, but was worried about breaking the filter trying to get enough leverage on the filter to turn it.
I used an Irwin 50mm quick grip spring hand clamp. ($8.45 at Bunnings)
Irwin 50mm quick grip spring clamp
These have a strong spring holding them closed, so once you've got them onto the filter you don't need to focus on gripping and turning to get the filter off.
Also the quick grips have rubberised clamps on the end, so it's less likely to break the filter.
With these grips I was easily about to unlock and remove the water filter.
Water filter information:
Model Code: HAF-CIN/EXP
Replacement Cartridge Code: DA29-00020B
For Use in System Model No.: DA97-08006A-E
Other fridge models this filter also works with and therefore this advice is probably also valid:
SRF653CDLS, SRF677CDBLS, SRF680CDLS, SRF679SWLS, SRF800WGDLS, SRF828SCLS, SRF800GDLS, SRF836WDRS, SRF867FSBLS, SRF886SCLS, SRF890SWLS, SRF1028CCRS, SRF717CDBLS, SRF719DLS, SRF924DLS, SRF731GDLS, SRF801GDLS, SRS877GDHLS