Remove alpha channel

I’m trying out your software as I need to convert  png files (example attached) to have a white background (not transparent)
I can’t work out how to do this with your software.
Is this possible?

You can use:

Files tab | Add files | Add your file

Actions tab | Add
Alpha Channel | Remove alpha channel
Background color | Click | select White color
Merge with background = ON
OK

Result tab | Output format = PNG

Start