[Lordyfrb]

I've just had a quick look at the code for SpartanUI and to remove the cast bar do the following:

Comment out the lines 150 to 171 inclusive from the file SpartanUI_PlayerFrames\Global-Framework.lua

do -- cast bar
            local cast = CreateFrame("StatusBar",nil,self);
            cast:SetFrameStrata("BACKGROUND"); cast:SetFrameLevel(2);
            cast:SetWidth(153); cast:SetHeight(16);
            cast:SetPoint("TOPLEFT",self,"TOPLEFT",36,-23);
            
            cast.Text = cast:CreateFontString(nil, "OVERLAY", "SUI_FontOutline10");
            cast.Text:SetWidth(135); cast.Text:SetHeight(11);
            cast.Text:SetJustifyH("RIGHT"); cast.Text:SetJustifyV("MIDDLE");
            cast.Text:SetPoint("LEFT",cast,"LEFT",4,0);
            
            cast.Time = cast:CreateFontString(nil, "OVERLAY", "SUI_FontOutline10");
            cast.Time:SetWidth(90); cast.Time:SetHeight(11);
            cast.Time:SetJustifyH("RIGHT"); cast.Time:SetJustifyV("MIDDLE");
            cast.Time:SetPoint("RIGHT",cast,"LEFT",-2,0);
            
            self.Castbar = cast;
            self.Castbar.OnUpdate = OnCastbarUpdate;
            self.Castbar.PostCastStart = PostCastStart;
            self.Castbar.PostChannelStart = PostChannelStart;
            self.Castbar.PostCastStop = PostCastStop;
        end

They'll be this bit of code, that creates the player cast bar, commenting out these will remove the built in one and enable the blizzard cast bar.

then you'll need to reanchor the health bar, so on line 176 there will be this:

health:SetPoint("TOPLEFT",self.Castbar,"BOTTOMLEFT",0,-2);

Change it to this:

health:SetPoint("TOPLEFT",self,"TOPLEFT",36,-39);

Hopefully this will help you out.