How to reverse the direction of the y axes

A little bit tricky because it is not supposed to work: ScallingFunctions are documented since V11 but this works for V10 and maybe erlier versions.

Plot[x^2, {x, 0, 3}, ScalingFunctions -> {Identity, "Reverse"}, 
                     PlotRange -> {{0, 4}, {-10, 0}}, 
                     AxesStyle -> {[email protected], Arrowheads[{-.05, 0}]}]

How can one find undocumented options

Not pretty, but using supported capabilities.

x = #^2 &@Range[0, 10, .001];

ListPlot[-x, DataRange -> {0, 10}, PlotStyle -> PointSize[.002], 
 InterpolationOrder -> 2, PlotRange -> {{0, 10}, {0, -100}}, 
 AxesOrigin -> {0, 0}, 
 Ticks -> {Automatic, 
   Function[{mn, mx}, 
    Table[{i, -i, {0.02, 0}}, {i, N@FindDivisions[{mn, mx}, 10]}]]}]