Use @Suppress annotation with argument "DEPRECATION":
@Suppress("DEPRECATION")
someObject.theDeprecatedFunction()
Instead of a single statement, you can also mark a function, a class or a file (@file:Suppress("DEPRECATION") in its beginning) with the annotation to suppress all the deprecation warnings issued there.
In IntelliJ IDEA this can also be done through Alt+Enter menu with caret placed on code with deprecation warning.