Strip first and last character from C string

Another option, again assuming that "edit" means you want to modify in place:

void topntail(char *str) {
    size_t len = strlen(str);
    assert(len >= 2); // or whatever you want to do with short strings
    memmove(str, str+1, len-2);
    str[len-2] = 0;
}

This modifies the string in place, without generating a new address as pmg's solution does. Not that there's anything wrong with pmg's answer, but in some cases it's not what you want.