To do so, using the computer version of Anki:
- Use File>Export to export your entire collection with scheduling information. This will give you a backup that you can restore to if anything goes wrong.
- Edit a card, and click the Cards... button.
- Look for areas in the front and back template that start with
<script>and end with
</script>. Remove the start and end, and everything in between.
- Confirm that the card displays in the review screen without error. If it's working ok, you can sync your changes to AnkiWeb and then to your other devices.
- If removing the script has completely broken the card, use File>Import to restore to the backup you created.