I would first suggest that other than a Compact & Repair as suggested by theDBguy, there is usually very little in the FE to be removed. The only things you can safely remove and maintain application functionality would be any obsolete items - like queries, forms, or reports that you never use any more. Beyond that, I'm not sure that you can remove much.
Now, if your FE is "impure" because you have included some tables in it, there MIGHT be some room for improvement. But the reason folks leave some tables in the FE is for isolation or temporary tables used for staging of data. But even there, if the functionality is needed, you won't be able to trim much.