Macro variables that are parameters to the macro program (yours are positional parameters) are LOCAL in scope to the Macro program. So when %func_1 is over, its macro variables are automatically "cleaned up" -- the LOCAL macro symbol table goes away when the macro program finishes. Unless those macro variables were previously defined to be GLOBAL in scope. The same applies to %func_2.
You might have referencing issues if %func_1 called %func_2 or vice versa. But generally you won't need to manually do any cleanup. Although if you DID need to ever do cleanup, there are ways to do it...from the simple %let:
%let var_list=; <--- which blanks out the macro variable value
to the complex -- the CALL SYMDEL or %SYMDEL statements (http://support.sas.com/documentation/cdl/en/mcrolref/59526/HTML/default/a001651249.htm ).