delete unwanted format strings

I have over time created format strings in the drop down list for tag-filename or filename- tag that have errors in them (extra spaces, expressions etc) How can I delete the erroneous ones and keep the one's I use?

You can delete them if you click on the button on the right site of the format string.

You have 2 possibilities:

  1. Delete them all
  2. Delete a singular shown string