If you need to remove one specific filter from all clips in project, do this:
Export fcpxml project file, open this file in TextEdit program, find and replace(CMD+F) all tags filter-video with name=“filter name”
If you need to remove Black & White filter, open fcpxml in text edit.
Find tag with parameter name="Black & White" he looks like this:
Done. Filter Black & White now removed. Save and import fcpxml back to Final Cut Pro X.
If you changed filter settings, tags look like that:
So, you can do this for filter-audio too.