@tom_dup_567 I think it could be in one of 2 spots. Open a workflow that uses that macro. 1) Go to Options >>> advanced options >>>> workflow dependencies. Click on show individual tools in blue at the top. If you see Excel File Opener, it should then have the filepath. If it's not there, then 2) Options >>>> User Settings >>> Edit User Settings. Click on the last tab macros. It will list macro repositories that you have setup. Excel File Opener should be in one of those folders.
Let me know if you can't find it!