unlinking excel and word documents

I have been making graphs on a daily basis on an excel spreadsheet and transferring the graph to a Word document so that I have months of daily graphs on word documents. I have now got an excel spreadsheet that seems to have linked itself to the word document I have opened to accept the daily graphs so that every time a new graph is drawn on the excel sheet all the previously drawn graphs for that month are altered to the latest graph (as would be the case if all the graphs were on the excel spreadsheet, a feature of excel that seems completely illogical to me as I can imagine no scenario where anyone would wish this to happen).
How can I unlink the spreadsheet and the word document?