Currently this can only be done via mods. As kju mentioned on Arma 3's Discord: "cfgActions can be modified via configs but not via sqf"
Forcing players to download mods for removing this alone can become a problem for mission makers who make vanilla/DLC missions without mod requirements, for missions already dependent on too many mods or for mission makers trying to avoid modding incompatibilities with future patches/other installed and enabled mods etc.
Arma 3's Default addActions such as the heal wounded action that appears on self and even on wounded enemies and can cause interference with custom made Medical Systems, custom Melee Systems and/or other scripted/modded alternatives for many of the default Arma 3 actions and interaction systems.
Other reason to include this functionality would be uncluttering the Action Menu. Currently some Action Menu options that pop up for example when having different ammo times for your current weapon etc can end up cluttering the already cumbersome Action Menu. On some missions where the action menu is already pretty cluttered can cause players to miss some key actions set by the mission maker and/or just make the menu really paintful to use.
And so it would be super helpful to let the mission maker disable these actions at discretion via SQF commands or perhaps something like the showHUD[] Description.ext param:
showDefaultActions[] = {
1, // Heal Action on wounded Friendlies
0, // Heal Action on wounded enemies
0, // Heal Action on Self
0, // Reload Weapon with XX type of Ammo
1, // Get In Vehicle
1, // Get Out Vehicle
1, // Put out/Start Fire
1, // Climb Ladder
1, // etc
1, // etc
1 // etc
};
Update based on the discussion on Arma 3's Discord Feeback Tracker Channel:
kju also suggested: "Probably better would be a way to disable them for entities altogether and script the still needed actions instead"
As Dedmen asked how ACE removed these actions [KP] veteran29 replied: "we change item type of FAK to not be a FAK anymore".
All illustrious participants Leopard20, Sparker, kju and of course [KP] veteran29 suggested a scripted solution rather than my original suggestion of a Description.ext param.
All involved did acknowledge that having such functionality would be very helpful for mission makers and even modders and mods that currently are forced to rely on various workarounds that can end up compromising their modularity, functionality, easy of use and customization options.