Below is a possible solution to Challenge 69 - Need Help in Not Showing Comments
These are not comments but Data Validation Messages..
Select the cell where pop up message is appearing > Data tab > Data Validation > The pop message is in the Input Message > Either you can remove messages or just say clear all.
To remove them in block -
1. Select rows 1 to 7 > Data tab > Data Validation > Clear All
2. Select rows 20 to 22 > Data tab > Data Validation > Clear All