Step 1
Create a new form with just the default submit button.
Go to Edit Form → Settings → General and turn off the Save submitted form data option.
Go to Edit Form → Settings → Style → Buttons and at the Submit button text enter the text for the submit button e.g. Logout
.
Go to Edit Form → Settings → Notifications and delete the Admin notification.
Go to Edit Form → Settings → Confirmations and go to the settings for the Default confirmation then at the Type option choose Reload the page, or choose Redirect to another page then choose a page to redirect to.
Step 2
Add the following code to the WordPress theme functions.php file (or create a plugin for it).