Correct.
But (in case of need) there is a workaround (assuming, args is an JSON-array of arguments):

kill tmp
set tmp=args.%Size()
for i=1:1:tmp set tmp(i)=args.%Get(i-1)
set resultSet = ##class(%SQL.Statement).%ExecDirect( , sql_whereClause, tmp...)

kill args
set args($i(args))="arg1"
set args($i(args))="arg2"
set args($i(args))="arg3"
...
set resultSet = ##class(%SQL.Statement).%ExecDirect( , sql_whereClause, args...)

RemoveDirectoryTree(some_dir) works, if it returns FALSE to you so
- either your Ensemble instance has no rights to delete files and directories
- or you feed RemoveDirrectoryTree() with a filename or with a  nonexistent directory

Try the following:

write FileUnZip,! // this should be an existing DIRECTORY
write ##class(%File).Attribute(FileUnZip),! // this should be 16 (on Windows)
write ##class(%File).RemoveDirectoryTree(FileUnZip),! // 1=removed, 0=not-removed