This is a rushed manual. The source code is annotated if you want to see how the utilities work.
Notes:
KillApps7 and InitApps7 are versions that use absolute addresses in the RO 3.70 rom. As a result, they are very small bits of code. They may work on RO 3.6 too, but not on earlier roms.
The applications for RO 3.50 were on the harddisc, so do not expect KillApps to do anything. You can use RemApp.
These utilities will not do anything useful on earlier syatems. I think they will not cause a crash, but there is no guarantee.
The applications killed in RO 3.70 are: !Alarm, !Chars, !Draw, !Edit, !Help, !Paint and !Printers. If I remember correctly, !Calc was in rom before !SciCalc was used, and it should be killed too. If !Configure was in rom, I think it added its own files, so would not be killed.
Usually, a later version of !Printers is added from disc. This will not be killed, but if you really want to, use RemApp.
For those who say "but I only want to get rid of !Edit" the answer is to take a soft copy of any rom applications you want from Resources:$.Apps to $.Apps on your Boot disc. They are only front ends to code elsewhere in rom, so there is little penalty.
InitApps uses two system variables set by KillApps, so if you use it first you will get a warning.
If you use KillApps (or InitApps) repeatedly, nothing more should happen after the first time, but there is intentionally no error.
AddApp is quite clever about what files it adds, and RemApp should deal with this. It should also release the RMA claimed by AddApp.
If no appname is given to RemApp a Syntax error is generated. If the appname does not exist in Resources:$.Apps there is intentionally no error.
I intend to incorporate these commands into RFSFiles in due course.
WARNING: Testing has been brief, so use these utilities with care. If there are still mistakes in the code which remove the bulk of rom messages, most of the OS will crash and you may need a power-off reset. However, I am fairly confident that this should no longer happen :-)