To suppress output, use redirection to NUL.
There are two kinds of output that console commands use:
standard output, or stdout,
standard error, or stderr.
Of the two, stdout is used more often, both by internal commands, like copy, and by console utilities, or external commands, like find and others, as well as by third-party console programs.
>NUL suppresses the standard output and works fine e.g. for suppressing the 1 file(s) copied. message of the copy command. An alternative syntax is 1>NUL. So,
COPY file1 file2 >NUL
or
COPY file1 file2 1>NUL
or
>NUL COPY file1 file2
or
1>NUL COPY file1 file2
suppresses all of COPY's standard output.
To suppress error messages, which are typically printed to stderr, use 2>NUL instead. So, to suppress a File Not Found message that DEL prints when, well, the specified file is not found, just add 2>NUL either at the beginning or at the end of the command line:
DEL file 2>NUL
or
2>NUL DEL file
Although sometimes it may be a better idea to actually verify whether the file exists before trying to delete it, like you are doing in your own solution. Note, however, that you don't need to delete the files one by one, using a loop. You can use a single command to delete the lot:
IF EXIST "%scriptDirectory%*.noext" DEL "%scriptDirectory%*.noext"