Class: Adding/Deleting/Output to file question

[shinyspear]

With the .txt file below for example. I need some suggestions how I can add information to the file, or delete a certain line, and how to save the changed .txt file and output it to output file.

Using dynamic array

// .txt file
ABC 000 1111
HELLO 111 1234
heyheyey 123 2345  //let's say I want to delete this line, how would I do that.
addthis 999 6969 //how would I add this to this file using class/dynamic arrays? 

Thanks