How do you reduce database size by deleting unused fields?

Delete the fields before the doc is saved by adding code like this to the fields' translation formula:

  @If (x="";  @DeleteField;  x)

Make sure the x's are exactly the field name, or you will loose data.
Do not delete fields if they are used in other formulas.

Applies to Notes Versions: 3, 4, 4.5, 4.6, 5