Hi Mark,
Unfortunately I do not have SAP_ALL in my system for me. But as far as I remember you should follow below path:
Goto Tcode SFW5:
Expand second node - scroll down and choose ENTERPRISE_BUSINESS_FUNCTIONS - FIN_REP_SIMPL_1 - Reporting Financials - check it and Activate changes
Then you might have to relogin again.
One more important thing: try this in Development System only first. Also really important to contact your FI team for impact analysis.
As far as I know these business functions are not possible to revert back 
Thanks
Amit