How can I reset quantity cells in Numbers without losing format?

Not sure what you are doing now that changes the format. Select all the cells and hit Delete. This will get rid of the numbers, leaving the cells blank without changing the format. Blank = 0 for math formulas. If you need it to actually show a zero, change one of them to 0 then Copy/Paste to the rest of them or Copy then Paste and Match Style if there are different borders or cell/text colors in different cells.

Here is a shortcut that will clear the contents of selected cells in a contiguous range. If your ten columns are all touching as one range you can clear them all. Or if the stuff between them needs cleared, too, you can clear all of it.

https://www.icloud.com/shortcuts/b30d4f9608654f32bab8e90466570a32

It deletes values, sets sliders and steppers to their minimum value, unchecks checkboxes, and sets pop ups to their "start with" item while not touching any formulas. First time you use it you may be asked to allow scripts to run in the Shortcut app.

It works on contiguous ranges: a cell, a rectangular range of cells, a column, touching columns, a row, touching rows. If you choose two random cells it will do all the cells between them as if you had selected a rectangular range and those were two corners of it.

Or you could use the other method I mentioned earlier (before I knew these were sliders): Set one slider to 0, Copy, select all the others, Paste. All will become sliders set to 0.

It was a lot less confusing when this forum was for the MacOS version of Numbers only. I don't think iOS supports AppleScript, which is why this shortcut won't run on iPad. The built-in shortcut actions for Numbers are very limited, nothing even near what you want to do.