I assume you are familiar with the top section of the mission sqm:
class Mission
{
addOns[]=
{
"bas_weap",
"JAM_Magazines",
"Ch47D",
"bis_resistance",
"bas_mh47185",
"BAS_MAH60",
"Vulcan",
"HMMWV",
"BAS_OPFOR",
"bas_o",
"bis_weaponpack",
"bas_deraJ",
"bas_soar185",
"editorupdate102",
"BAS_Jkawa",
"bas_kawa"
};
addOnsAuto[]=
{
"JAM_Magazines",
"bas_deraJ",
"BAS_OPFOR",
"Ch47D",
"BAS_Jkawa",
"bas_kawa",
"bas_mh47185",
"BAS_MAH60",
"Vulcan",
"bis_resistance",
"HMMWV",
"bas_o",
"editorupdate102"
};
In this example you need to delete the lines starting with BAS_, JAM_, and the editorupdate102 to make it addonFree. Do this after exchanging the units for BIS units in the editor, and hiting save in the editor.
Make sure you also change all units in any intro or outro in the editor that comes with the mission. Then scroll to the bottom of the mission.sqm and you will find this:
class Intro
{
addOns[]=
{
"BAS_OPFOR",
"Ch47D",
"HMMWV",
"JAM_Magazines"
};
addOnsAuto[]=
{
"BAS_OPFOR",
"Ch47D",
"HMMWV",
"JAM_Magazines"
};
Again, you have to go through the whole process. The same goes for Outro Win and Outro Lose.
I often overlook the fact that the addonslist are repeated at the bottom of the page when I edit my mission.sqm. Maybe that's your problem.