Unable to modify/delete custom styles

Hello all,
I need help with libreoffice portable (winxp).
I created some custom cell styles to apply a conditional formatting.
Now I’d want to either modify or delete them.
When I right click on the style name and choose modify, nothing happens; when I choose delete, it appears a dialog box to confirm the style deletion, but then the style is not deleted.
What can I do?
Thank you in advance.

Perhaps the problem is caused by setting the interface language (IMHO). Try this macro - change value of Const prefixStyleName to name of your style and run it

Hi Anonymous, Did @JohnSUN’s comment help you out? Are you still looking for an answer to your question?

Years Late, but this could be caused by a sheet being locked.