How to change a letter in a char pointer?

This pointer comes from a function like this, and I want to remove a part of the string

Code:

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void search(char *DirectoryPath)

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Code:

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#include <stdio.h>
int main() {
  // How do I make it work?
  char *A = "Slackware";
  A[5] = '\0';
  puts(A); // Slack

  // It works! char A[] = "Slackware";
}

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Well there are pointers to memory you can't change, such as
char *A = "Slackware";

Which should be declared as const to begin with.

Code:

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$ cat foo.c
#include <stdio.h>
#include <stdlib.h>
int main()
{
    char *A = "Slackware";
    puts(A);
    return 0;
}
$ gcc -Wall -Wextra -Wwrite-strings foo.c
foo.c: In function ‘main’:
foo.c:5:15: warning: initialization discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
    5 |    char *A = "Slackware";
      |              ^~~~~~~~~~~

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Then there are pointers to memory you can change.

Code:

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$ cat foo.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main()
{
    char *A = malloc(20);
    strcpy(A,"Slackware");
    A[5] = '\0';
    puts(A);
    free(A);
    return 0;
}
$ gcc -Wall -Wextra -Wwrite-strings foo.c
$ ./a.out
Slack

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