Your old IT person may have used a Visual Integrator import job that would update the AP_Vendor table on the fields VendorStatus and InactiveReasonCode.

But how would they get the data to complete the import?  I understand that we can do an import but I'd have to compile the data for the file prior to sending to IT.  I'd be looking to figure out if there was anything in the system that would kick a report back stating either the last date used or who we haven't used in the last # of years, depending on our criteria.  

Have you considered reaching out to your Reseller of Record? If you are not aware of who that is, Sage Software can assist you and put you in touch with them.  What you are describing is not a "feature of the software", but certainly possible.  Write a crystal report to determine what vendors are over 5-years inactive and create a list of only those vendors.  Write a Visual Integrator Import to update the vendor master with the Inactive Setting and any reason code you associated in your crystal report (probably exported to excel for manipulation); then saved as a .csv file for importing the inactive flag. 

This is very helpful, thank you!  I don't personally but I bet IT does.  I'll share with them and move on from there.