Is there any way to "unmerge" Bookmarks and History after disabling iCloud Syncing on Safari?

Recently, I logged in to iCloud from my MacBook. When it asked me if I wanted to merge my bookmarks and Reading List with iCloud, I carelessly clicked yes, and continued on my business for the next couple of days. Eventually I realised that as a result of my actions, my history, reading list, and bookmarks on my iPhone and other iDevices signed into iCloud were merged with my Mac. Wanting to undo this, I unchecked Safari from the iCloud menu, and sure enough, it stopped syncing, but the leftover merged history, reading list and bookmark entries remained on my MacBook. Is there any way to delete these entries while preserving my original search history, bookmarks and reading list entries? Thanks.