Delete iMessage chat history from work MacBook How do I delete all the iMessage chat history and logs from my work MacBook but still have them on my iPhone (they are synced).

The Mac is running macOS Mojave 10.14.
You can simply disable the iMessage account on your Mac.

Open Messages app preferences (by using keyboard shortcut Command + ,), go to iMessage tab. Under Settings just below your Apple ID, uncheck Enable this account.