Green and orange lines in an empty-intended Plot?

Questions
1

Iā€™m trying to make an empty 2D graph, but I keep getting these strange green and orange lines, how do I get rid of them?

Plot[
{x,6,-1},
{y,6,-1},
AxesLabel -> {x,y}
]
2

This way you are in fact plotting 3 functions: ā€œxā€, which is not depending on y (your variable) and so it is undefined and not shown, and the constant functions ā€œ6ā€ and ā€œ-1ā€ (the colored lines). You probably rather want:

Plot3D[Nothing, {x, 6, -1}, {y, 6, -1}, AxesLabel -> {x, y}]