You can try three ways. But they are not all perfect.
The first is based on the difference in the quality of grinding sugar and salt. If the salt is Extra, then its grains are noticeably smaller than that of granulated sugar. I don’t remember what this method is called, but they are still miners who separate ordinary sand from gold. A description is probably not required.
And the second method is based on the fact that the solubility of the salt is slightly lower than that of sugar. So it should dissolve the mixture in water, before supersaturation, at a temperature close to boiling, and stirring to cool to zero degrees. Salt will precipitate. Remove sediment. This operation should be performed several times. Until the taste of the solution you feel that there is only one sugar left in it. Then you need to evaporate the excess water, and again begin to repeatedly carry out this procedure. Evaporate excess water and then cool. Then sugar starts to fall out.
And the third method is based on the difference in the density of aqueous solutions of salt and sugar. Salt should be diluted in water and allowed to settle. Then the solution will delaminate. A denser saline solution will lie at the bottom. A lighter sugar concentrates on the surface. Then you can gently pump out the top layer, constantly trying it on the tongue. And then, separated solutions, rid of sugar and salt, by the method specified in the second method.