I'd use the keepchars() function to keep only the necessary characters. To generate the string of characters to keep, you can use the workflow below.
keepchars.morph (4.9 KB)
Alternatively, use the new "Generate expression" feature of the Expression Editor. It suggested using a regular expression. I'm not a fan of regular expressions, but it does the job.
regexreplace([TEXT], "", "[\u007F-\uFFFF]")