You should be able to use a screwdriver to loosen the clips, then rotate the clip arms so they no longer "grab" the countertop. Then pull the sink upwards and off the countertop.

Sealant is usually applied between the rim of the sink and the countertop, making it difficult to release the rim of the sink off the counter. How much and what type of sealant depends on the model and age of the sink and the installer.

once you get the clips out of the way, a good means to break the sink loose of the countertop is to place a car jack under the sink and sloooooooooooooooooooowly start putting pressure on it. If you are lucky, the old sealant will let go and the sink will pop out.

"sloooooooooooooooooooowly start putting pressure on it"

If you try this use some 2x lumber to spread the jack force on the bottom of the sink.

Cutting the sealer (putty knives, old paring knife, razor blades) is usually adequate.

Thanks for the replies, but there is no screw or arm on these clips; they look like springs, that's why I was asking about removal - thought they might be some specialized Euro thingy.