How do I delete matches instead of replacing them?

Leave "Replace with" empty. Every match is removed.

Is "$" treated specially?

Only in regular expression mode, where $1 refers to the first captured group. In plain mode the replacement is inserted exactly as typed.

No. The text is processed in your browser as you type and is never uploaded or stored.

JavaScript is turned off. InspireTools processes files in your browser, so the tools need JavaScript to run.

Replace words or patterns across a block of text, with regular expression support.