Stopping 1 part of the code is unnecessary because SmileBASIC is not multithreaded.
However, to stop loops, use BREAK, to stop a subroutine (gosub), use RETURN, and you can use large IF statements or labels to stop functions.
Are any of these what you mean?
the 'contest' you started is using characters that would earn you any submission a copyright strike, read the eula again before doing another. in short unless its your own ip you cant use it