How to run as user from elevated main program

[hdt888]

My main program runs with admin rights (elevated process).
When I use RunProgram() command and call another exe program, this program also runs with admin rights.
This is understandable.
How do I call another program (using RunProgram() command) to run with user rights ( = non-elevated process ) ?
How to run child process non-elevated from an elevated/As Admin process ?

[Little John]

For Windows, this has been discussed in this thread.