Complex sentence: Paskevich demanded that Warsaw and Praga be surrendered unconditionally and that Polish Army be evacuated and disarmed in Płock, where it was to await the decision of the tsar who would then either pardon the Polish soldiers or imprison them as rebels.
Split into simpler sentences: Paskevich demanded that Warsaw and Praga be surrendered unconditionally and that Polish Army be evacuated and disarmed in Płock. The Russian commander insisted that the Poles sign unconditional surrender and withdraw to Płock, where the Polish Army was to await the decision of the tsar who would then either pardon them or imprison them as rebels.