This Screen Shot is from eclipse ide . It does not allow me use 

.delete

 method and show me as an error . Why does it behaving like this? How could i overcome this ? Kindly provide me a solution for this . Thanks in advance. Good day!

Don’t know about eclipse, Checking parenthesis, commas might help. you can try copy pasting the code to the actual script in NS, that might tell you better. or try VS code.

ignore that error. eclipse just considers delete as a reserved word. If you look at it, its the same color as the other reserved words

Eclipse's JavaScript support is only up to ES3, which is severely out of date. NetSuite is also ending support for Eclipse, so it is recommended to eventually move to VS Code or WebStorm for future SuiteScript development. Both of those will handle modern JavaScript much, much better than Eclipse.

Use vscode and SDF it's better

if you decide to go the vscode route, I strongly recommend using alongside with: https://github.com/headintheclouddev/typings-suitescript-2.0 (it is not necessary to use TypeScript fully to leverage the intellisense this types library provides - simply to have a similar jsconfig.json configured and use with JS as usual)