wrong result of deleting and destroy

[Maxing1997]

here is my examples

$ ./a.out 
89 48 63 2 5 28 6 

Option
1. Insert
2. Delete
3. Destroy
--------------------
What do you want? : 2
Data : 48
21881 48 63 2 5 28 

Option
1. Insert
2. Delete
3. Destroy
--------------------
What do you want? : 3
double free or corruption (out)

You can see when delete 48, 48 is still here!!! In fact, the data to delete seems always to be the last one in array by reading the source code, so I suggest remove the data option in delete. And also the random value is caused by read unintialized value.

Also, the destroy operation also can't work.