Using Import records to move the records to another table is an option that may be worth the trouble to set up. This table can be in the same file.
Other ways to "hide" records:
Mark these records by setting a field in them to a value that you don't set on the records you don't want to hide.
Use script triggers and scripts to perform finds/constrain found sets to keep them out of found sets. Show all records and show omitted only can still reveal them, but if you have FileMaker Advanced, you can set up your layouts with a custom menu that either omits these menu options or replaces them with options that "Show all", but still omit the records you want to hide.
Record Level Access control can be used via manage|Security to make these records inaccessible to all but full access users. Any find performed while the file is open with any such account will automatically omit "no access" records. See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis" for a description of how to set this up.