remove source file from project

We are using Netbeans in class, and something really bothers me. In Visual Studio, if I am working on several different files for different problems, I can just right click on the source file, choose remove, and add my new source file and compile the new program.
In Netbeans there is no remove, just a delete, and I found out the hard way that deletes the file off of the disk(after spending 3 hours writing it). Is there a way that I can do this without having to create a new project for each of the 10 problems we have in this assignment?

Why remove it?
I have a scratch project in which I dump all my brain fart code. Snippets for reading files, parsing xml, db code, image stuff, anything I happen to be testing out how it works (POI most recently). I haven't had to do a new project for each one, just either alter an existing main() or add a new one for running that particular thing.

If you have spent 3hrs for writing code why delete it? Why not just keep it safe somewhere.
and if you 10 problems, then just create single project and write code in that project with different file name like(MyFirst.java, MySecond.java). To run MyFirst.java then i would do "Shift + F6" (This help to run single file not the entire project).

-Regards