It is very easy to delete the last rows or columns in a boost::multi_array, for example, using the following minimal example:

#include "boost/multi_array.hpp"
#include <iostream>

typedef boost::multi_array<double, 2> array_type;

// Helper function for printing arrays
void print_array(const array_type& A){
  for ( size_t i=0; i < A.shape()[0]; i++ ) {
    for ( size_t j=0; j < A.shape()[1]; j++ )
      std::cout << A[i][j] << " ";
    std::cout << std::endl;
  }
}

int main () {
  
  // Create a 2D array that is 5 x 3
  size_t dims[2] = {5, 3};
  array_type A(boost::extents[dims[0]][dims[1]]);

  // Assign values to the elements
  int values = 0;
  for(size_t i = 0; i < A.shape()[0]; ++i) {
    for(size_t j = 0; j < A.shape()[1]; ++j) {
        A[i][j] = values;
    }
    values++;
  }

  // Print the array
  std::cout << "A:" << std::endl;
  print_array(A);

  // Delete rows and print the array again
  A.resize(boost::extents[3][A.shape()[1]]);
  std::cout << std::endl << "A after resizing:" << std::endl;
  print_array(A);
  
  return 0;
}

This code produces the following output:

A:
0 0 0 
1 1 1 
2 2 2 
3 3 3 
4 4 4 

A after resizing:
0 0 0 
1 1 1 
2 2 2 

As one can see, the resize operation simply deleted the last rows of the array.

Question: Would it be possible to delete the first rows (or columns) instead, such that the output of the program would become

A:
0 0 0 
1 1 1 
2 2 2 
3 3 3 
4 4 4 

A after resizing:
2 2 2 
3 3 3 
4 4 4 

Thank you very much in advance for your help!