An automatically deleting of all completed Apple reminders on macOS every hour

deleteAppleCompletedReminders.md

1. Copy the deleteCompletedReminders.scpt file to your directory (for example, xxx).
2. In the deleteCompletedReminders.plist file change the PATH_TO_YOUR_SCRIPT constant to the path to your xxx directory.
3. Copy the deleteCompletedReminders.plist file to the /Library/LaunchAgents/ directory.
4. Restart your computer.
5. The deleting script will be executed on every login (may ask for some permissions for the first time) and every 24 hours.

deleteCompletedReminders.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Disabled</key>
    <false/>
    <key>Label</key>
    <string>deleteCompletedReminders</string>
    <key>Program</key>
    <string>/usr/bin/osascript</string>
    <key>ProgramArguments</key>
    <array>
      <string>osascript</string>
      <string>PATH_TO_YOUR_SCRIPT/deleteCompletedReminders.scpt</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>StartInterval</key>
    <integer>3600</integer>
  </dict>
</plist>

deleteCompletedReminders.scpt

tell application "Reminders" to delete (reminders whose completed is true)