As mentioned, there is no way to "delete" them - this would leave you with no beats. If the goal is just to print blank manuscript, select all with Ctrl+A and make invisible with "V". If you just want to enter notes, no need to waste time deleting rests first - just enter the notes - they will automatically replace the rests, keeping the correct number of beats at all times.
Comments
You can't. Why do you want to delete them? Someone can explain how to accomplish what you want.
Blank manuscript?
See:
https://musescore.org/en/node/90251
As mentioned, there is no way to "delete" them - this would leave you with no beats. If the goal is just to print blank manuscript, select all with Ctrl+A and make invisible with "V". If you just want to enter notes, no need to waste time deleting rests first - just enter the notes - they will automatically replace the rests, keeping the correct number of beats at all times.