Numbers: how to replace formula cell with its result?

I have a sheet with a column of numbers (A), all negative, that I needed to change to positive. I used this suggestion to apply a formula to create a new column (B) with the numbers positive.

That worked, but I want to delete the original column of negative numbers, and when I do that, the new column numbers all turn to zero because the formula depends on column A.

So how can I convert column B to keep the formula numbers AND delete column A?

IOW, 1st row, column B now says 4. If I delete column A, it changes to 0. How do I get it to stick with 4 permanently, without the existence of column A's -4?