Hi Grit, there isn't an 'option' to do this, but if you attempt to delete the calculated field Tableau will pop up a warning that lists fields (in current worksheet) and the other sheets that use the calculation, like this:
Careful though, if the calculation isn't being used in the workbook at all, then it will be deleted without warning, so be ready with the back button.
this was the woraround I used .
Would be great to have this functionality in a next release. I'll request it.