We are trying to delete some inactive records from Marketo, but I want those records to stay in SFDC and I have 2 questions:
If I delete the records in Marketo, will it also delete them from SFDC?
Assuming that if we delete the records from Marketo, it will not delete them from SFDC, will SFDC push those records back into Marketo when it syncs at midnight?
The answer is that SFDC will push them again to SFDC if and only if the records have been updated in SFDC.
If you want to prevent thos from happening, you need to implement a sync filter and make sure you are flagging these records in SFDC so that they stop sync'ing.
Some reading about this:
Tacking onto what Greg said, the flow step for delete lead also has a dropdown for "Delete from CRM?"
As long as that's set as "FALSE," you won't delete records in your CRM (SFDC).