One trick you could do is rename the folder of the Wwise Project.
For instance, if you rename this...
SomeWwiseProject > SomeWwiseProject_WwiseProject.wproj
... to this...
SomeWwiseProject_Hidden > SomeWwiseProject_WwiseProject.wproj
... it won't show up in the Launcher.
That said, this will probably also break the link from your e.g. Unity project.
So instead, if you want to hide an entire e.g. Unity project from the Launcher while keeping the Unity/Wwise project linked, you can rename the Unity project folder (the parent folder of your Asset folder).
Let me know if this helps!