Here's what I believe the verbiage is (as well as the Sage KB link) to remove a form code manually:
Link:
http://infosource.sagesoftwareonline.com/sw_attach/kdb.asp?isresolutionconceptid=492199
Subject:
How to remove graphical form codes not listed in Report Manager for Sage MAS 90 and 200
Possible Resolution:
References to the form code must be removed manually:
Expand Modules, Library Master, and Utilities. Double-click Data File Display and Maintenance (DFDM).
In the File Name field, select the ...\MAS_SYSTEM\SY_ReportSetting.M4T file.
Delete the key associated with the form code. Repeat this step for the following files:
SY_ReportOption.M4T
SY_LastFormUsed.M4T
In Windows Explorer, browse to the ...\MAS90\MAS_xxx\Reports\ folder.
Delete the folder associated with the form code.