I created a record in Zoho Books, synced it to Zoho CRM, and later deleted it in Zoho CRM. Will the record be deleted in Zoho Books as well?

No, the record will not be deleted in Zoho Books.

Also, if the record (created in Zoho Books) is deleted in Zoho Books, it will not affect the corresponding record in Zoho CRM.

However, if you have created a record in Zoho CRM, synced it to Zoho Books, and deleted it in Zoho CRM, the record will either be deleted in Zoho Books, if there are no transactions associated with it, or marked as inactive.