Look at what
Modify EPUB Plugin can do
Please 'More Input' when asking these kinds of questions
You did not specify 'for what format'.
A case like this is why I hate the Nuke'em all CSS, Image, Font removal suggestions. The cleanup of the aftermath is bad and a lot harder.
Get proficient with the Editor and you will spend 5 mins or less on most (Original source), books making them
your way.
Eg. I remove embedded Charis fonts .
Step 1 is use the debug tool to make sure the book was Valid TO START
Step 2 In the book Browser: Select all Charis...
elete
Step 3 In the debug screen:remove all references... (will need to do for each face you removed)
Save
Fixing Step 1 errors is the biggest time suck
I have clips I replace bits IN THE CSS
I remove The Sample chapters (I leave the 1 page ad if separate)
I have no use for an inline TOC if the NCX is fine.
YMMV but the point I am trying to make is Knowledge can make it fairly fast.
Aftermath cleanup is hard