how can i delete useless variables from cpp progrmas code example

Example 1: c++ delet from memory

// Delete pointer
int* ptr1 = new int;
delete ptr1;

// Delete array
int* array = new int[10];
delete[] array;

Example 2: dynamic memory allocation in c++

char* pvalue  = NULL;         // Pointer initialized with null
pvalue  = new char[20];       // Request memory for the variable