How do you delete BOM Files in Big Sur

Package receipts including .bom files are stored on the System read-only partition, and you do not remove them for that reason.

If it means so much to you to perform unnecessary maintenance, create another startup drive to boot from, then remove the files you want to remove. Nothing should stop you from removing them if you boot from another drive.

You could do it from Recovery using Terminal, but that would take a bit more learning.

Have you noticed, me included, that no one wants to invest time performing cleanup on the older systems where one could do so without encountering a read only System partition — before upgrading? It is on us, not Apple, but it is easier to shift blame. 🥸