Thanks for you question,
Here are the steps to apply,
Method 1 : easy one :
Use "Data cleansing" and check : "Remove null rows" in the configuration window.
Method 2 : In case you want more advanced cleaning.
1. Use the "Union Tool" to combine all the 3 files one one output.
2. Use the tool crosse tab to "transpose tool" : in the configuration window (on the left side of the screen), you can select the columns that contain null rows in "data columns".
3. Use a filter on the newly created column "value" and set it to "is not null"
4. Use the Crosstab tool :Group data by => Leave it empty / Change column headers chose : "Name", / Values for new columns chose "Value", and apply the "sum" as aggregating method.
Attached an example of the workflow.
If this answer is helpful, please check it as "solution", this will help other beginners find it easily 🙂