OK, I understand what you mean. I did the test.
As far as I know, the cache of your page in Google will be refreshed soon (it could be in some days/weeks) by itself (normally).
I understood that you do not want to remove totally the page from Google to prevent to loose visitors, but if you do not have too much visitor (less than 100 per days on the Home page), don't worry, you can remove it totally, Google will explore your website in the next few days and your Home page will come back in Google.
Step 1 :
To proceed this way, first you have to use a file called robots.txt, if you already use a robots.txt file, do a backup of this file onto your local computer because we need to change it temporarily.
As Google said with the message "For permanent removal, the content must be blocked by robots.txt."
With a text editor, create a new file called robots.txt and copy/paste this :
Then save the file and upload it in your www web folder. This will block Google indexing in your entire website (always temporarily)
Step 2 :
In the Google Webmaster Tools, simply click "remove URL", click "New remove request" then leave blank the URL field and click "OK"
Now, Google has the request to remove the Home page URL, but you'll have to wait 1 or 2 days, it's important that you wait while keeping this new robots.txt file present in www.
Sometimes, You can check removal requests status in "Remove URLs" in the Google Webmaster Tool. Once the URL seems to be deleted from Google, delete our robots.txt file from your server and/or replace it by the one you backuped before this operation)