Question: Is there any security options to limit a user's ability to submit data using excel?

• Submitting data via excel will respect the security model set up in OneStream. So consider typical security setup. Also consider using constraints to manage "valid" data intersections. 
• Inputting data via set cell will get tracked in the audit logs, however, clearing this data can be problematic if you wish to clear all out all submitted cells. Rather than using set cell, another option is to set up an excel import which would go through stage and allow for clearing of the data set.    
• There is a pending enhancement request to have an option available to restrict some users from submitting via excel.

Source: Office Hours 2020-7-2 - Partner Enablement