How to add/delete a column without changing the size of the other columns

Hi,

Our wiki TDF has an article «How to add/delete a column without changing the
size of the other columns» [1]. I can not achieve the expected result when I
follow this instruction. Perhaps, something is missing there or there is
another way to do it.
Thanks for any ideas.

Lera.

[1] https://wiki.documentfoundation.org/Faq/Writer/161