Assuming Netbeans 7.0 +
Select Tools in the top menu bar.
-> Options
-> click on the Editor (looks like a book)
-> select the tab that says "hints"
-> from the drop-down menu, select the correct language
-> deselect for this function
If this is a documentation request message, then
-> select the tab that says "Code Completion"
-> uncheck the box "Automatic pop-up window"
Neatbeans, HINTS DOCs , , , ...