If you have copied the wrong data into one of your budget years, you can zero it using the copy function.
Each of our budget scenarios can host multiple years of data, and it's useful to copy previous year's actual data into your budget so that your users can see the previous years' totals in the Data Sheet as they build their budgets.
To copy this data into your budget you would go to Data/Formulas > Copy Data, and choose the Copy Multiple Departments option (the first in the list) from the menu at the top left of the screen.
You would then maybe choose your Actuals 2020 as the source budget, and 2020 as your source year, and choose Budget 2021 as the target budget, making sure to choose 2020 for the target year(it will default to 2021, which is your budget data).
If you have accidentally copied the wrong data, and you wish to zero that data, you would use the same function, but this time you would choose a source year which you know to be zero - for instance 2025, and copy that to the year in the target budget which has the data that needs to be deleted. This will have the effect of overwriting your erroneous data with zeroes.
Make sure to select All Departments and All Categories, and to check the Overwrite Data box.