Is it possible to ask Mathematica to crop a specified area in the given plot? or, is it possible to manually erase redundant part of a plot?

Question

I am using this code

pic1 = GridGraph[{19, 10}, PlotRange -> {-10, 10}];
pic2 = Graphics[ {{Inset[Style["text", Black, FontSize -> Scaled[0.1], FontFamily -> "Times"], {5, 5}] } } ]  ;
pic3 = Show[{pic1, pic2}] ;
pic4 = Graphics[ {LightRed, Rotate[Rectangle[{30, 30}, {50, 10}], 45 Degree]} ,ImageSize -> 200 ] ;

Overlay[{pic4, pic3}] 

and the result is $Fig1$. I have two questions:

Q1. How can I ask Mathematica to crop only the red area and give a result like Fig2? or, alternatively, is it possible to manually erase/remove the unwanted area in Fig1 and then export it as a PDF file?

Q2. Is it possible to control the position of the red square in Fig1 (the corresponding code pic4)? For example, moving it a bit to the right?

Answer 1

Unfortunately RegionFunction doesn't work with Graphics or Show, sorry for my misleading hint in my comment.

As a workaround you might use a "passepartout" and mask your plot (see helpful answer from @Domen RegionFunction inside Show )

your modified plot(without masking, I changed Overlay to Show):

pic1 = GridGraph[{11, 10} ];
pic2 = Graphics[{{Text(*Inset*)[Style["text", Black, FontSize ->Scaled[0.1],FontFamily -> "Times"], {5, 5}]}}];
pic = {pic1, pic2} ;

reg = TransformedRegion[ Rectangle[{5, 3 }, {10, 8}] ,RotationTransform[Pi/4, {5, 3}]];
pic4 = Graphics[{LightRed, reg} ];

Show[{pic4, pic  } ]

final picture with passepartout:

frame = Rectangle [ {0, 0}, {11, 12}]; (* not to small*)
mask = BoundaryDiscretizeRegion[RegionDifference[frame, reg], 
MaxCellMeasure -> 1/30 , MeshCellStyle -> {1 -> None, 2 -> White}];

Show[{pic4, pic, mask  }  ]

The final picture might be clipped using PlotRange

Hope it helps!