Action to delete values of specific columns

[Skip2MiLu]

I have columns from called 1 to 53 that are decimal column types
I am looking for an action that will delete or clear values of these columns. 
I initially thought that using either a action with "" or just leave blank (like for column 5), would clear the values, but I see it actually returns a 0 instead of clearing the value completely if I look at my underlying table. 

However the values of the columns for that row is cleared if edit each and delete them manually (look at columns 1 to 5 in which I did this. 
However using an action with "" or leaving blank return a zero instead no value (look at columns 6-10).

How can I go creating an action that will clearing the values instead of returning a 0. 

[Suvrutt_Gurjar]

In the action's "set these columns" expressions, please try an expression of DECIMAL("") instead of just "".

However please note that any blank column in a record is NOT displayed in the detail view. The detail view needs the column to have a non blank value to display it.