This code defines a function called StripPinyin which takes a string argument and returns a modified version of the string with pinyin tones removed.
It can be called from within another macro or function, or from a cell in a Calc spreadsheet by using the formula =StripPinyin("pinyin string").
For instance =StripPinyin("Wǒ mǎshàng jiù huílái.") will yield "Wo mashang jiu huilai."
Simply import StripPinyin.bas as a macro in LibreOffice Calc (should also work on Excel and Google Sheets).