Changing Notes rests - AaronDavidNewman/Smoosic GitHub Wiki
You can toggle notes to rests by pressing r or Delete.
In Smoosic, you can't truly delete a note - a 4/4 bar will always have 4 beats of music. But you can 'hide' notes by creating invisible rests. This is another use of Delete.
Delete follows standard toggle behavior - deleted notes become rests, and delete rests become invisible rests. Hitting Delete a third time restores the note.
Invisible rests show up as partially opaque in the display. But when printed, they are truly invisible.