On Colt 1911's and most rifles- removal of a dovetail sight is by using a brass drift and driving the sight OUT from LEFT to RIGHT (looking at the slide as though you were shooting). Also suggest using a LARGE hammer and one good WACK to break it loose rather than a lot of "baby taps" that can cause more damage to the sight.
When it comes to Nordinkos ... anything goes ... who knows ... but first try the above procedure.